DBI-1.612 > DBI

名前

DBI - Database independent interface for Perl

DBI - Perl 用データベース独立インターフェース

概要

  use DBI;

  @driver_names = DBI->available_drivers;
  %drivers      = DBI->installed_drivers;
  @data_sources = DBI->data_sources($driver_name, \%attr);

  $dbh = DBI->connect($data_source, $username, $auth, \%attr);

  $rv  = $dbh->do($statement);
  $rv  = $dbh->do($statement, \%attr);
  $rv  = $dbh->do($statement, \%attr, @bind_values);

  $ary_ref  = $dbh->selectall_arrayref($statement);
  $hash_ref = $dbh->selectall_hashref($statement, $key_field);

  $ary_ref  = $dbh->selectcol_arrayref($statement);
  $ary_ref  = $dbh->selectcol_arrayref($statement, \%attr);

  @row_ary  = $dbh->selectrow_array($statement);
  $ary_ref  = $dbh->selectrow_arrayref($statement);
  $hash_ref = $dbh->selectrow_hashref($statement);

  $sth = $dbh->prepare($statement);
  $sth = $dbh->prepare_cached($statement);

  $rc = $sth->bind_param($p_num, $bind_value);
  $rc = $sth->bind_param($p_num, $bind_value, $bind_type);
  $rc = $sth->bind_param($p_num, $bind_value, \%attr);

  $rv = $sth->execute;
  $rv = $sth->execute(@bind_values);
  $rv = $sth->execute_array(\%attr, ...);

  $rc = $sth->bind_col($col_num, \$col_variable);
  $rc = $sth->bind_columns(@list_of_refs_to_vars_to_bind);

  @row_ary  = $sth->fetchrow_array;
  $ary_ref  = $sth->fetchrow_arrayref;
  $hash_ref = $sth->fetchrow_hashref;

  $ary_ref  = $sth->fetchall_arrayref;
  $ary_ref  = $sth->fetchall_arrayref( $slice, $max_rows );

  $hash_ref = $sth->fetchall_hashref( $key_field );

  $rv  = $sth->rows;

  $rc  = $dbh->begin_work;
  $rc  = $dbh->commit;
  $rc  = $dbh->rollback;

  $quoted_string = $dbh->quote($string);

  $rc  = $h->err;
  $str = $h->errstr;
  $rv  = $h->state;

  $rc  = $dbh->disconnect;

The synopsis above only lists the major methods and parameters.

上記の概略は主なメソッドとパラメータだけをリストにしています。

助けを得る

If you have questions about DBI, or DBD driver modules, you can get help from the dbi-users@perl.org mailing list. You don't have to subscribe to the list in order to post, though I'd recommend it. You can get help on subscribing and using the list by emailing dbi-users-help@perl.org.

DBI や DBD ドライバモジュールに関する質問があるなら、 dbi-users@perl.org メーリングリストで助けを得られます。 投稿するのにメーリングリストの購読は必要ではありませんが、購読することを 勧めます。 dbi-users-help@perl.org にメールすることで、メーリングリストの購読および 使用に関する助けが得られます。

I don't recommend the DBI cpanforum (at http://www.cpanforum.com/dist/DBI) because relatively few people read it compared with dbi-users@perl.org.

私は DBI cpanforum (at http://www.cpanforum.com/dist/DBI) は勧めません; dbi-users@perl.org に比べて読んでいる人数が少ないからです。

To help you make the best use of the dbi-users mailing list, and any other lists or forums you may use, I strongly recommend that you read "How To Ask Questions The Smart Way" by Eric Raymond: http://www.catb.org/~esr/faqs/smart-questions.html.

dbi-users メーリングリストや、その他のメーリングリストやフォーラムを うまく利用するために、私は Eric Raymond による "How To Ask Questions The Smart Way" http://www.catb.org/~esr/faqs/smart-questions.html (和訳:「賢い質問のしかた」 http://www.ranvis.com/articles/smart-questions.ja.html) を 読むことを 強く 勧めます。

If you think you've found a bug then please also read "How to Report Bugs Effectively" by Simon Tatham: http://www.chiark.greenend.org.uk/~sgtatham/bugs.html.

バグを発見したと思ったら、Simon Tatham による "How to Report Bugs Effectively" http://www.chiark.greenend.org.uk/~sgtatham/bugs.html (和訳: 「効果的にバグを報告するには」 http://www.chiark.greenend.org.uk/~sgtatham/bugs-jp.html) も 読んでください。

The DBI home page at http://dbi.perl.org/ and the DBI FAQ at http://faq.dbi-support.com/ are always worth a visit. They include links to other resources.

http://dbi.perl.org/ の DBI ホームページと http://faq.dbi-support.com/ の DBI FAQ は常に訪れる価値のある場所です。 これらには他のリソースへのリンクもあります。

Before asking any questions, reread this document, consult the archives and read the DBI FAQ. The archives are listed at the end of this document and on the DBI home page.

質問をする前に、このドキュメントを読み返し、アーカイブをあたり、DBI FAQ を 読んでください。 アーカイブはこのリストの最後と DBI ホームページに一覧があります。

This document often uses terms like references, objects, methods. If you're not familiar with those terms then it would be a good idea to read at least the following perl manuals first: perlreftut, perldsc, perllol, and perlboot.

この文書にはしばしば リファレンス, オブジェクト, メソッド といった 用語を使います。 これらの用語に親しみがないなら、少なくとも以下のマニュアルを先に読むのが いい考えです: perlreftut, perldsc, perllol, perlboot

Please note that Tim Bunce does not maintain the mailing lists or the web page (generous volunteers do that). So please don't send mail directly to him; he just doesn't have the time to answer questions personally. The dbi-users mailing list has lots of experienced people who should be able to help you if you need it. If you do email Tim he is very likely to just forward it to the mailing list.

Tim Bunce がそのメーリングリストや Web ページを管理しているわけでは ないことに注意してください(通常はボランティアがやっています)。 そのため彼に直接メールを送らないで下さい; 彼には個人的に質問に答える時間が ないだけです。 dbi-users メーリングリストは経験豊富な人たちがたくさんいて、必要であれば あなたを助けてくれるでしょう。 Tim にメールしても、おそらく単にメーリングリストに転送されるでしょう。

注意

This is the DBI specification that corresponds to the DBI version 1.612 ($Revision: 14216 $).

これは DBI バージョン1.612 ($Revision: 14216 $) に対応した DBI の仕様です。

The DBI is evolving at a steady pace, so it's good to check that you have the latest copy.

DBI の仕様は、現在、確実なペースで更新されています。 最新のものを持っているかをチェックしてください。

The significant user-visible changes in each release are documented in the DBI::Changes module so you can read them by executing perldoc DBI::Changes.

リリース毎のユーザーに見える重要な変更は DBI::Changes モジュールに 文書化されているので、perldoc DBI::Changes を実行することで これを読むことができます。

Some DBI changes require changes in the drivers, but the drivers can take some time to catch up. Newer versions of the DBI have added features that may not yet be supported by the drivers you use. Talk to the authors of your drivers if you need a new feature that is not yet supported.

DBI の変更によってドライバの変更が必要になる場合もありますが、 ドライバは追いつくのに少し時間がかかります。 新しいバージョンの DBI は、今使っているドライバではまだ対応していない 機能を追加していることもあります。 もしまだ対応していない新しい機能が必要なら、ドライバの作者に 話してみてください。

Features added after DBI 1.21 (February 2002) are marked in the text with the version number of the DBI release they first appeared in.

DBI 1.21 (2002 年 2 月) 以降に追加された機能については、最初に 追加された DBI リリースのバージョン番号を文章中に記しています。

Extensions to the DBI API often use the DBIx::* namespace. See "Naming Conventions and Name Space". DBI extension modules can be found at http://search.cpan.org/search?mode=module&query=DBIx. And all modules related to the DBI can be found at http://search.cpan.org/search?query=DBI&mode=all.

DBI API のエクステンションはしばしば DBIx::* 名前空間が使われます。 "Naming Conventions and Name Space" を参照してください。 DBI エクステンションモジュールは http://search.cpan.org/search?mode=module&query=DBIx にあります。 DBI 関連の全てのモジュールは http://search.cpan.org/search?query=DBI&mode=all にあります。

説明

The DBI is a database access module for the Perl programming language. It defines a set of methods, variables, and conventions that provide a consistent database interface, independent of the actual database being used.

DBI は Perl プログラミング言語のためのデータベースアクセスモジュールです。 それはセットになったメソッド、変数そして規約を定義し、実際の使われている データベースに依存しない一貫性のあるデータベースインターフェースを 提供します。

It is important to remember that the DBI is just an interface. The DBI is a layer of "glue" between an application and one or more database driver modules. It is the driver modules which do most of the real work. The DBI provides a standard interface and framework for the drivers to operate within.

DBI が単なるインターフェースであることを忘れないことは重要です。 DBI はアプリケーションと一つまたは複数のデータベース ドライバ モジュールとを結び付ける薄い「糊」の層なのです。 実際に働くのはドライバモジュールです。 DBI はドライバを操作するための標準のインターフェースと枠組みを提供します。

DBI アプリケーションのアーキテクチャ

             |<- Scope of DBI ->|
                  .-.   .--------------.   .-------------.
  .-------.       | |---| XYZ Driver   |---| XYZ Engine  |
  | Perl  |       | |   `--------------'   `-------------'
  | script|  |A|  |D|   .--------------.   .-------------.
  | using |--|P|--|B|---|Oracle Driver |---|Oracle Engine|
  | DBI   |  |I|  |I|   `--------------'   `-------------'
  | API   |       | |...
  |methods|       | |... Other drivers
  `-------'       | |...
                  `-'

The API, or Application Programming Interface, defines the call interface and variables for Perl scripts to use. The API is implemented by the Perl DBI extension.

API、つまりアプリケーション・プログラミング・インターフェースは Perl スクリプトが使うための呼び出しインタフェースと変数を定義します。 API は Perl DBI エクステンションによって実装されます。

The DBI "dispatches" the method calls to the appropriate driver for actual execution. The DBI is also responsible for the dynamic loading of drivers, error checking and handling, providing default implementations for methods, and many other non-database specific duties.

DBI は適切なドライバへ実際の実行のためにメソッド呼び出しを 「発行」(dispatch)します。 DBI はドライバの動的なロード、エラーのチェック/操作、メソッドのための デフォルトの実装の提供、その他たくさんのデータベース特有なこと以外にも 責任を持ちます。

Each driver contains implementations of the DBI methods using the private interface functions of the corresponding database engine. Only authors of sophisticated/multi-database applications or generic library functions need be concerned with drivers.

各ドライバは対応するデータベースエンジンのプライベートなインターフェース 関数を使い、DBI メソッドの実装を持ちます。 高度な/複数のデータベースに対応するアプリーケーションや 汎用ライブラリ関数の作成者だけが、このドライバに関心をもつ必要があります。

記法と規約

The following conventions are used in this document:

このドキュメントでは以下の表記法を使用します:

  $dbh    Database handle object
  $sth    Statement handle object
  $drh    Driver handle object (rarely seen or used in applications)
  $h      Any of the handle types above ($dbh, $sth, or $drh)
  $rc     General Return Code  (boolean: true=ok, false=error)
  $rv     General Return Value (typically an integer)
  @ary    List of values returned from the database, typically a row of data
  $rows   Number of rows processed (if available, else -1)
  $fh     A filehandle
  undef   NULL values are represented by undefined values in Perl
  \%attr  Reference to a hash of attribute values passed to methods
  $dbh    データベースハンドルオブジェクト
  $sth    文ハンドルオブジェクト
  $drh    ドライバハンドルオブジェクト(アプリケーションで目にしたり、使ったりすることはまずありません)
  $h      上記のハンドルのどれか
  $rc     一般的な戻り値(コード)(真偽値: 真=OK, 偽=エラー)
  $rv     一般的な戻り値(値) (通常はinteger)
  @ary    データベースから返される値のリスト。通常はデータの行
  $rows   処理された行の数 (もしあれば。なければ -1)
  $fh     ファイルハンドル
  undef   Perl では NULL値は未定義値で表現される
  \%attr  メソッドに渡される属性値のハッシュのリファレンス

Note that Perl will automatically destroy database and statement handle objects if all references to them are deleted.

注意:そこへの参照がすべて削除されると、Perl は、自動的にデータベースと ステートメントオブジェクトを破壊します。

使用法の概要

To use DBI, first you need to load the DBI module:

DBI を使うためには、まず DBI モジュールをロードする必要があります:

  use DBI;
  use strict;

(The use strict; isn't required but is strongly recommended.)

(use strict; は必須ではありませんが、強く推奨します。)

Then you need to "connect" to your data source and get a handle for that connection:

そしてデータソースに接続("connect")し、その接続のための ハンドル を取得します:

  $dbh = DBI->connect($dsn, $user, $password,
                      { RaiseError => 1, AutoCommit => 0 });

Since connecting can be expensive, you generally just connect at the start of your program and disconnect at the end.

接続にはコストがかかるので、一般的にはプログラムの開始した時点で接続し、 終わりで切断します:

Explicitly defining the required AutoCommit behaviour is strongly recommended and may become mandatory in a later version. This determines whether changes are automatically committed to the database when executed, or need to be explicitly committed later.

要求される AutoCommit の動きを明示的に定義することは強く推奨されます。 将来のバージョンでは必須になるかもしれません。 これは実行したときに変更を自動的にデータベースにコミットするか、後から 明示的にコミットされる必要があるかを決定します。

The DBI allows an application to "prepare" statements for later execution. A prepared statement is identified by a statement handle held in a Perl variable. We'll call the Perl variable $sth in our examples.

DBI では、アプリケーションはSQL文を後で実行するための "prepare"(=準備)をしておくことができます。 prepare された文は Perl 変数に入った文ハンドルにより 識別されます。 この例ではその Perl 変数を $sth とします。

The typical method call sequence for a SELECT statement is:

SELECT 文のための典型的なメソッドの順番は以下のようになります:

  prepare,
    execute, fetch, fetch, ...
    execute, fetch, fetch, ...
    execute, fetch, fetch, ...

for example:

例:

  $sth = $dbh->prepare("SELECT foo, bar FROM table WHERE baz=?");

  $sth->execute( $baz );

  while ( @row = $sth->fetchrow_array ) {
    print "@row\n";
  }

The typical method call sequence for a non-SELECT statement is:

SELECT以外 のための典型的なメソッドの順番は 以下のようになります:

  prepare,
    execute,
    execute,
    execute.

for example:

例:

  $sth = $dbh->prepare("INSERT INTO table(foo,bar,baz) VALUES (?,?,?)");

  while(<CSV>) {
    chomp;
    my ($foo,$bar,$baz) = split /,/;
        $sth->execute( $foo, $bar, $baz );
  }

The do() method can be used for non repeated non-SELECT statement (or with drivers that don't support placeholders):

do() メソッドは繰り返されない SELECT 以外 の文のために (またはプレースホルダをサポートしないドライバで)使うことができます:

  $rows_affected = $dbh->do("UPDATE your_table SET foo = foo + 1");

To commit your changes to the database (when "AutoCommit" is off):

データベースへの変更をコミットするためには("AutoCommit" がオフの時):

  $dbh->commit;  # or call $dbh->rollback; to undo changes

Finally, when you have finished working with the data source, you should "disconnect" from it:

最後に、データソースでの作業を終了するときにはそこから 切断("disconnect" )しなければいけません:

  $dbh->disconnect;

一般的なインターフェース規則と留意事項

The DBI does not have a concept of a "current session". Every session has a handle object (i.e., a $dbh) returned from the connect method. That handle object is used to invoke database related methods.

DBI には「現在のセッション」という考えはありません。 各セッションは connectメソッドから返されるハンドルオブジェクト (つまり $dbh)を持ちます。 そのハンドルオブジェクトがデータベース関連のメソッドを呼び出すために 使われます。

Most data is returned to the Perl script as strings. (Null values are returned as undef.) This allows arbitrary precision numeric data to be handled without loss of accuracy. Beware that Perl may not preserve the same accuracy when the string is used as a number.

ほとんどのデータは文字列として Perl スクリプトに返されます(Null 値は undef として返されます)。 これにより任意の桁数の数値データを精度を落とすことなく扱うことができます。 文字列を数値として扱う際に、Perl が同じ精度を保たないかも しれないということに注意してください。

Dates and times are returned as character strings in the current default format of the corresponding database engine. Time zone effects are database/driver dependent.

日付(Date)、時刻(Time)は、対応するデータベースエンジンの現在の デフォルトフォーマットの文字列として返されます。 時間帯の影響はデータベース/ドライバに存します。

Perl supports binary data in Perl strings, and the DBI will pass binary data to and from the driver without change. It is up to the driver implementors to decide how they wish to handle such binary data.

Perl スクリプトは文字列のなかにあるバイナリデータをサポートします。 DBI はバイナリデータを変更することなく、ドライバとやりとりします。 そのようなバイナリデータをどのように扱いたいのかを決めることはドライバの 実装者次第です。

Perl supports two kinds of strings: Unicode (utf8 internally) and non-Unicode (defaults to iso-8859-1 if forced to assume an encoding). Drivers should accept both kinds of strings and, if required, convert them to the character set of the database being used. Similarly, when fetching from the database character data that isn't iso-8859-1 the driver should convert it into utf8.

Perl は 2 種類の文字列に対応しています: Unicode (内部では utf8) と 非-Unicode (もしエンコーディングを仮定することを強制されるなら デフォルトは iso-8859-1)。 ドライバはどちらの種類の文字列も受け付けて、もし必要ならデータベースが 使っている文字集合に変換できるべきです。 同様に、iso-8859-1 でない データベース文字データをフェッチしたときには、 ドライバは utf8 に変換するべきです。

Multiple SQL statements may not be combined in a single statement handle ($sth), although some databases and drivers do support this (notably Sybase and SQL Server).

データベース、ドライバによってはそれをサポートしているとしても (特に Sybaseと SQL Server)、複数の SQL 文は1つの 文ハンドル($sth)に結び付けられないかもしれません。

Non-sequential record reads are not supported in this version of the DBI. In other words, records can only be fetched in the order that the database returned them, and once fetched they are forgotten.

このバージョンの DBI では順序通りでないレコードの読み込みはできません。 いいかえればレコードは、データベースが返してきた順序にしか 取り出すことはできませんし、一度取り出されると忘れ去られてしまいます。

Positioned updates and deletes are not directly supported by the DBI. See the description of the CursorName attribute for an alternative.

位置づけての更新、削除を DBI は直接サポートしていません。 その代わりとして CursorName 属性の説明をご覧ください。

Individual driver implementors are free to provide any private functions and/or handle attributes that they feel are useful. Private driver functions can be invoked using the DBI func() method. Private driver attributes are accessed just like standard attributes.

各ドライバを実装する開発者は、使いやすいと思えば、プライベートな関数や 属性を自由に提供することができます。 プライベートなドライバ関数は DBI の func() メソッドを使って 呼び出すことができます。 プライベートなドライバ属性は標準の属性とまったく同じように アクセスすることができます。

Many methods have an optional \%attr parameter which can be used to pass information to the driver implementing the method. Except where specifically documented, the \%attr parameter can only be used to pass driver specific hints. In general, you can ignore \%attr parameters or pass it as undef.

多くのメソッドはオプションとして \%attr パラメータを受け取ります。 これを使ってドライバが実装しているメソッドに情報を渡すことができます。 特に記述されていなければ、\%attr パラメータは特定のヒントを渡す場合にのみ 使用されます。 普通は \%attr パラメータを無視するか undef を渡すことができます。

命名規則と名前空間

The DBI package and all packages below it (DBI::*) are reserved for use by the DBI. Extensions and related modules use the DBIx:: namespace (see http://www.perl.com/CPAN/modules/by-module/DBIx/). Package names beginning with DBD:: are reserved for use by DBI database drivers. All environment variables used by the DBI or by individual DBDs begin with "DBI_" or "DBD_".

DBI パッケージとその下のパッケージ(DBI::*) は、DBI によって 予約されてます。 エクステンションと関連するモジュールは DBIx:: 名前空間 (http://www.perl.com/CPAN/modules/by-module/DBIx/をご覧下さい)を使います。 DBD:: で始まるパッケージ名は DBI データベースドライバによって 使うように予約されています。 DBI または各 DBD によって使われるすべての環境変数は "DBI_" または "DBD_" で始まります。

The letter case used for attribute names is significant and plays an important part in the portability of DBI scripts. The case of the attribute name is used to signify who defined the meaning of that name and its values.

属性の名前に使われる文字の大文字/小文字の区別は、DBI スクリプトの 移植性において重要で大きな役割を果たしています。 属性の名前が大文字か小文字かによって、名前と値を誰が決めたのかを示すのに 使われています。

  Case of name  Has a meaning defined by
  ------------  ------------------------
  UPPER_CASE    Standards, e.g.,  X/Open, ISO SQL92 etc (portable)
  MixedCase     DBI API (portable), underscores are not used.
  lower_case    Driver or database engine specific (non-portable)
  名前の大文字/小文字   説明
  ---------------------- -------------------------------------------
  大文字のみ(UPPER_CASE) 標準、つまり X/Open, SQL92 など(移植性あり)
  混合(MixedCase)        DBI API(移植性性あり)アンダースコア(_)は使わない
  小文字のみ(lower_case) ドライバもしくはエンジンに特有(移植性なし)

It is of the utmost importance that Driver developers only use lowercase attribute names when defining private attributes. Private attribute names must be prefixed with the driver name or suitable abbreviation (e.g., "ora_" for Oracle, "ing_" for Ingres, etc).

最も重要なのはドライバ開発者はプライベートな属性を定義するとき、小文字の 属性しか使ってはいけないといことです。 プライベートな属性の名前は、ドライバ名もしくは適切な略語から始まらなければ なりません。 (例えば ora_ はOracle, ing_ は Ingres など).

SQL - 問い合わせ言語

Most DBI drivers require applications to use a dialect of SQL (Structured Query Language) to interact with the database engine. The "Standards Reference Information" section provides links to useful information about SQL.

大半の DBI ドライバではデータベースエンジンとのやりとりに、それぞれの SQL(Structured Query Language) を使うことが要求とします。 "Standards Reference Information" 章は SQL に関する有用な情報への リンクを提供しています。

The DBI itself does not mandate or require any particular language to be used; it is language independent. In ODBC terms, the DBI is in "pass-thru" mode, although individual drivers might not be. The only requirement is that queries and other statements must be expressed as a single string of characters passed as the first argument to the "prepare" or "do" methods.

DBI 自身は特定の言語を使うことを必須とも必要ともしていません;言語から 独立しています。 ODBC の用語でいうとDBI は「パススルー」モード(='pass-thru' mode)に あたります。 各ドライバはそうでないかもしれません。 唯一必要なことは、"prepare" または "do" メソッドへの最初の引数として 渡される問い合せまたはその他の文は、文字による一つの文字列として 表現されなければならないことです。

For an interesting diversion on the real history of RDBMS and SQL, from the people who made it happen, see:

RDBMS と SQL の 本当の 歴史についての興味深いこぼれ話が、実際にそれを やった人達から出されています:

  http://ftp.digital.com/pub/DEC/SRC/technical-notes/SRC-1997-018-html/sqlr95.html

Follow the "Full Contents" then "Intergalactic dataspeak" links for the SQL history.

SQLの歴史については "Full Contents" から "Intergalactic dataspeak" リンクを追ってみてください。

プレースホルダとバインド値

Some drivers support placeholders and bind values. Placeholders, also called parameter markers, are used to indicate values in a database statement that will be supplied later, before the prepared statement is executed. For example, an application might use the following to insert a row of data into the SALES table:

ある種のドライバはプレースホルダとバインド値をサポートしています。 プレースホルダはパラメータ・マーカーとも呼ばれ、データベース文の 中の値が後で、準備(prepare)された文が実行される前に 与えられることを示すために使われます。 例えば、以下のようにして、SALES テーブルに行を挿入することができます:

  INSERT INTO sales (product_code, qty, price) VALUES (?, ?, ?)

or the following, to select the description for a product:

あるいは PRODUCTS テーブルから製品の説明 (description) を取得できます

  SELECT description FROM products WHERE product_code = ?

The ? characters are the placeholders. The association of actual values with placeholders is known as binding, and the values are referred to as bind values. Note that the ? is not enclosed in quotation marks, even when the placeholder represents a string.

? という文字がプレースホルダです。 実際の値とプレースホルダとの結びつけが バインド(binding)で、値は バインド値(bind values) として呼ばれます。 プレースホルダが文字列を表わしているとしても、? が クォーテーションマークで囲まれていないことに注意してください。

Some drivers also allow placeholders like :name and :N (e.g., :1, :2, and so on) in addition to ?, but their use is not portable.

ドライバによっては、? だけでなく、:名前:番号 (例えば :1, :2 など)といった形式のプレースホルダを 許しているものもありますが、それは移植可能ではありません。

If the :N form of placeholder is supported by the driver you're using, then you should be able to use either "bind_param" or "execute" to bind values. Check your driver documentation.

使っているドライバが :N 形式のプレースフォルダに対応しているなら、 値をバインドするのに "bind_param" あるいは "execute" を使えるべきです。 ドライバの文書をチェックしてみて下さい。

With most drivers, placeholders can't be used for any element of a statement that would prevent the database server from validating the statement and creating a query execution plan for it. For example:

データベースサーバでの文の評価ができず、そのため問い合わせ 計画を作成できなくなるために、多くのドライバではプレースホルダをすべての 文の要素として使えるということではありません。 例えば:

  "SELECT name, age FROM ?"         # wrong (will probably fail)
  "SELECT name, ?   FROM people"    # wrong (but may not 'fail')

Also, placeholders can only represent single scalar values. For example, the following statement won't work as expected for more than one value:

またプレースホルダは一つのスカラ値だけを表わします。 例えば以下の文は複数の値を期待してもうまくいかいないでしょう:

  "SELECT name, age FROM people WHERE name IN (?)"    # wrong
  "SELECT name, age FROM people WHERE name IN (?,?)"  # two names

When using placeholders with the SQL LIKE qualifier, you must remember that the placeholder substitutes for the whole string. So you should use "... LIKE ? ..." and include any wildcard characters in the value that you bind to the placeholder.

プレースホルダを SQL の LIKE 修飾子と使う場合には、プレースホルダは 文字列全体を置き換えることを忘れてはいけません。 そのため "... LIKE ? ..." を使い、プレースホルダにバインドする値に ワイルドカードとなる文字をすべて入れなければなりません。

NULL Values

NULL 値

Undefined values, or undef, are used to indicate NULL values. You can insert and update columns with a NULL value as you would a non-NULL value. These examples insert and update the column age with a NULL value:

未定義値 (undef) は NULL 値を示すのに使われます。 非 NULL 値と同様、NULL 値で列を挿入および更新できます。 以下は age 列を NULL 値で挿入および更新する例です:

  $sth = $dbh->prepare(qq{
    INSERT INTO people (fullname, age) VALUES (?, ?)
  });
  $sth->execute("Joe Bloggs", undef);

  $sth = $dbh->prepare(qq{
    UPDATE people SET age = ? WHERE fullname = ?
  });
  $sth->execute(undef, "Joe Bloggs");

However, care must be taken when trying to use NULL values in a WHERE clause. Consider:

しかし WHERE 句で NULL 値を使う場合には特に注意が必要です。 以下のような場合について考えてみましょう:

  SELECT fullname FROM people WHERE age = ?

Binding an undef (NULL) to the placeholder will not select rows which have a NULL age! At least for database engines that conform to the SQL standard. Refer to the SQL manual for your database engine or any SQL book for the reasons for this. To explicitly select NULLs you have to say "WHERE age IS NULL".

undef (NULL) をプレースホルダにバインドしても、NULLの age を持つ行は 何も 選択されません! 少なくとも SQL 標準に準拠いているデータベースエンジンではそうです。 この理由については、使用しているデータベースエンジンの SQL のマニュアル または SQL の解説書をご覧ください。 明示的に NULL を SELECT するためには "WHERE age IS NULL"とする必要が あります。

A common issue is to have a code fragment handle a value that could be either defined or undef (non-NULL or NULL) at runtime. A simple technique is to prepare the appropriate statement as needed, and substitute the placeholder for non-NULL cases:

よくある問題の一つは、実行時に definedundef か (非 NULL か NULL か)決定される値を扱うためのコードがあるときです。 簡単なテクニックは、必要に応じて適切な分を準備して、非 NULL の場合の プレースフォルダを置き換えることです:

  $sql_clause = defined $age? "age = ?" : "age IS NULL";
  $sth = $dbh->prepare(qq{
    SELECT fullname FROM people WHERE $sql_clause
  });
  $sth->execute(defined $age ? $age : ());

The following technique illustrates qualifying a WHERE clause with several columns, whose associated values (defined or undef) are in a hash %h:

以下のテクニックは、結びつける値 (defined or undef) がハッシュ %h に 入っている複数の列の WHERE 句の作成方法を示しています:

  for my $col ("age", "phone", "email") {
    if (defined $h{$col}) {
      push @sql_qual, "$col = ?";
      push @sql_bind, $h{$col};
    }
    else {
      push @sql_qual, "$col IS NULL";
    }
  }
  $sql_clause = join(" AND ", @sql_qual);
  $sth = $dbh->prepare(qq{
      SELECT fullname FROM people WHERE $sql_clause
  });
  $sth->execute(@sql_bind);

The techniques above call prepare for the SQL statement with each call to execute. Because calls to prepare() can be expensive, performance can suffer when an application iterates many times over statements like the above.

上述のテクニックは実行するそれぞれの呼び出しの SQL 文のために prepare を 呼び出します。 prepare() の呼び出しはコストが高いので、上述のようにアプリケーションが 文を何回も繰り返すと性能に影響を与えるかもしれません。

A better solution is a single WHERE clause that supports both NULL and non-NULL comparisons. Its SQL statement would need to be prepared only once for all cases, thus improving performance. Several examples of WHERE clauses that support this are presented below. But each example lacks portability, robustness, or simplicity. Whether an example is supported on your database engine depends on what SQL extensions it provides, and where it supports the ? placeholder in a statement.

よりよい解決法は、NULL と非 NULL 比較の両方に対応した単一の WHERE 句です。 この SQL 文は全ての場合に置いて 1 回だけ prepare する必要があるので、 性能が向上します。 これに対応するためのいくつかの WHERE 句の例を以下に示します。 しかしそれぞれの例には互換性、堅牢性、単純性に欠けています。 あなたが使うデータベースエンジンでどの例が対応しているかは、 どの SQL 拡張を提供しているかと、文中のどこに ? プレースホルダが 対応しているかに依存します。

  0)  age = ?
  1)  NVL(age, xx) = NVL(?, xx)
  2)  ISNULL(age, xx) = ISNULL(?, xx)
  3)  DECODE(age, ?, 1, 0) = 1
  4)  age = ? OR (age IS NULL AND ? IS NULL)
  5)  age = ? OR (age IS NULL AND SP_ISNULL(?) = 1)
  6)  age = ? OR (age IS NULL AND ? = 1)

Statements formed with the above WHERE clauses require execute statements as follows. The arguments are required, whether their values are defined or undef.

上述の WHERE 句の形式の文は、以下のように文を実行する必要があります。 値が definedundef かを示す引数が必要です。

  0,1,2,3)  $sth->execute($age);
  4,5)      $sth->execute($age, $age);
  6)        $sth->execute($age, defined($age) ? 0 : 1);

Example 0 should not work (as mentioned earlier), but may work on a few database engines anyway (e.g. Sybase). Example 0 is part of examples 4, 5, and 6, so if example 0 works, these other examples may work, even if the engine does not properly support the right hand side of the OR expression.

例 0 は(前述したように)動作しないかもしれませんが、それでも(Sybase のような) いくつかのデータベースエンジンでは動作します。 例 0 は例 4, 5, 6 の一部なので、例 0 が動作すれば、例えエンジンが OR 式の 右側を正しく対応していないとしても、他の例も動作します。

Examples 1 and 2 are not robust: they require that you provide a valid column value xx (e.g. '~') which is not present in any row. That means you must have some notion of what data won't be stored in the column, and expect clients to adhere to that.

例 1 と 2 は頑強ではありません: これらは、どの行にも存在しない、 有効な列の値 xx (例えば '~') を提供することを求められます。 これにより、どのデータがその列に保管できないのかについて注意を 払わなければならず、クライアントがそれに従うことを 想定しなければなりません。

Example 5 requires that you provide a stored procedure (SP_ISNULL in this example) that acts as a function: it checks whether a value is null, and returns 1 if it is, or 0 if not.

例 5 は、関数のように動作するストアドプロシージャ (例えば SP_ISNULL) を 提供する必要があります: これは値が null かどうかをチェックして、そうなら 1 を、さもなければ 0 を返します。

Example 6, the least simple, is probably the most portable, i.e., it should work with with most, if not all, database engines.

例 6 は一番複雑ですが、おそらく一番移植性があります; つまり、 (全てでないとしても)ほとんどのデータベースエンジンで動作するはずです。

Here is a table that indicates which examples above are known to work on various database engines:

以下は様々なデータベースエンジンに対してどの例が動作すると分かっているかの 表です:

                   -----Examples------
                   0  1  2  3  4  5  6
                   -  -  -  -  -  -  -
  Oracle 9         N  Y  N  Y  Y  ?  Y
  Informix IDS 9   N  N  N  Y  N  Y  Y
  MS SQL           N  N  Y  N  Y  ?  Y
  Sybase           Y  N  N  N  N  N  Y
  AnyData,DBM,CSV  Y  N  N  N  Y  Y* Y
  SQLite 3.3       N  N  N  N  Y  N  N

* Works only because Example 0 works.

* 例 0 が動作する場合にのみ動作します。

DBI provides a sample perl script that will test the examples above on your database engine and tell you which ones work. It is located in the ex/ subdirectory of the DBI source distribution, or here: http://svn.perl.org/modules/dbi/trunk/ex/perl_dbi_nulls_test.pl Please use the script to help us fill-in and maintain this table.

DBI は、上述の例をあなたのデータベースでテストして動作するかどうかを 知らせてくれるサンプル perl スクリプトを提供しています。 これは DBI ソース配布の ex/ サブディレクトリか、以下の場所にあります: http://svn.perl.org/modules/dbi/trunk/ex/perl_dbi_nulls_test.pl スクリプトを、この表を埋めて保守する助けに使ってください。

Performance

性能

Without using placeholders, the insert statement shown previously would have to contain the literal values to be inserted and would have to be re-prepared and re-executed for each row. With placeholders, the insert statement only needs to be prepared once. The bind values for each row can be given to the execute method each time it's called. By avoiding the need to re-prepare the statement for each row, the application typically runs many times faster. Here's an example:

プレースホルダを使わなければ、上記の INSERT 文は挿入する値をリテラルで 入れなければなりませんし、各行毎に再準備(re-prepare)し、 再実行(re-execute)しなければいけません。 プレースホルダを使うと、INSERT 文を準備(prepare)する必要があるのは 1 回だけです。 各行のバインド値は execute メソッドを呼び出すときに与えることができます。 各行毎に再準備(re-prepare)する必要がなくなるので、アプリーケーションは 通常、何倍も速くなります。 以下に例を示します:

  my $sth = $dbh->prepare(q{
    INSERT INTO sales (product_code, qty, price) VALUES (?, ?, ?)
  }) or die $dbh->errstr;
  while (<>) {
      chomp;
      my ($product_code, $qty, $price) = split /,/;
      $sth->execute($product_code, $qty, $price) or die $dbh->errstr;
  }
  $dbh->commit or die $dbh->errstr;

See "execute" and "bind_param" for more details.

詳細は "execute" および "bind_param" をご覧ください。

The q{...} style quoting used in this example avoids clashing with quotes that may be used in the SQL statement. Use the double-quote like qq{...} operator if you want to interpolate variables into the string. See "Quote and Quote-like Operators" in perlop for more details.

この例では、SQL 文のなかで使われるかもしれないクォートの対応が崩れないよう、 q{...} スタイルのクォートを使っています。 文字列に解釈して欲しい変数がある場合には、qq{...} のような ダブルクォートを使うことができます。 詳細については "Quote and Quote-like Operators" in perlop をご覧ください。

See also the "bind_columns" method, which is used to associate Perl variables with the output columns of a SELECT statement.

Perl の変数を SELECT 文の出力カラムに結びつけるために使われる "bind_column" メソッドもご覧ください。

DBI パッケージとクラス

In this section, we cover the DBI class methods, utility functions, and the dynamic attributes associated with generic DBI handles.

このセクションでは、DBI クラスメソッド、ユーティリティ関数そして 一般的な DBI ハンドルに関連する動的属性についてカバーします。

DBI 定数

Constants representing the values of the SQL standard types can be imported individually by name, or all together by importing the special :sql_types tag.

以下の SQL 標準型定数は個別にインポートしたり、特殊な :sql_types タグで すべてをインポートすることができます:

The names and values of all the defined SQL standard types can be produced like this:

定義されている全ての SQL 標準型の名前と値は以下のようにして取得できます:

  foreach (@{ $DBI::EXPORT_TAGS{sql_types} }) {
    printf "%s=%d\n", $_, &{"DBI::$_"};
  }

These constants are defined by SQL/CLI, ODBC or both. SQL_BIGINT is (currently) omitted, because SQL/CLI and ODBC provide conflicting codes.

これらの定数は SQL/CLI, ODBC あるいは両方で定義されています。 SQL/CLI と ODBC でコードが衝突しているので、SQL_BIGINT is (現状では) 省略されています。

See the "type_info", "type_info_all", and "bind_param" methods for possible uses.

可能な利用法に関しては "type_info", "type_info_all", "bind_param" メソッドを参照してください。

Note that just because the DBI defines a named constant for a given data type doesn't mean that drivers will support that data type.

あるデータ型について DBI が名前付き定数を定義していないからと言って、 ドライバがそのデータ型に対応していないというわけではないことに 注意してください。

DBI クラスメソッド

The following methods are provided by the DBI class:

DBI クラスによって以下のメソッドが提供されています:

parse_dsn

  ($scheme, $driver, $attr_string, $attr_hash, $driver_dsn) = DBI->parse_dsn($dsn)
      or die "Can't parse DBI DSN '$dsn'";

Breaks apart a DBI Data Source Name (DSN) and returns the individual parts. If $dsn doesn't contain a valid DSN then parse_dsn() returns an empty list.

DBI データソース名(Data Source Name) (DSN) を分解して、それぞれの部分を 返します。 $dsn に有効な DSN が含まれていない場合、parse_dsn() は空リストを返します。

$scheme is the first part of the DSN and is currently always 'dbi'. $driver is the driver name, possibly defaulted to $ENV{DBI_DRIVER}, and may be undefined. $attr_string is the contents of the optional attribute string, which may be undefined. If $attr_string is not empty then $attr_hash is a reference to a hash containing the parsed attribute names and values. $driver_dsn is the last part of the DBI DSN string. For example:

$scheme は DSN の最初の部分で、現在のところ常に 'dbi' です。 $driver はドライバ名で、おそらくデフォルトは $ENV{DBI_DRIVER} で、 未定義値かもしれません。 $attr_string はオプションの属性文字列の内容で、未定義値かもしれません。 $attr_string が空でないなら、$attr_hash はパースされた属性名と値を含む ハッシュへのリファレンスです。 $driver_dsn は DBI DSN 文字列の最後の部分です。 例えば:

  ($scheme, $driver, $attr_string, $attr_hash, $driver_dsn)
      = DBI->parse_dsn("DBI:MyDriver(RaiseError=>1):db=test;port=42");
  $scheme      = 'dbi';
  $driver      = 'MyDriver';
  $attr_string = 'RaiseError=>1';
  $attr_hash   = { 'RaiseError' => '1' };
  $driver_dsn  = 'db=test;port=42';

The parse_dsn() method was added in DBI 1.43.

parse_dsn() メソッドは DBI 1.43 で追加されました。

connect

  $dbh = DBI->connect($data_source, $username, $password)
            or die $DBI::errstr;
  $dbh = DBI->connect($data_source, $username, $password, \%attr)
            or die $DBI::errstr;

Establishes a database connection, or session, to the requested $data_source. Returns a database handle object if the connection succeeds. Use $dbh->disconnect to terminate the connection.

要求された $data_source への接続またはセッションを確立します。 接続が成功するとデータベース・ハンドル・オブジェクトを返します。 接続を終わらせるためには $dbh->disconnect を使います。

If the connect fails (see below), it returns undef and sets both $DBI::err and $DBI::errstr. (It does not explicitly set $!.) You should generally test the return status of connect and print $DBI::errstr if it has failed.

connect が失敗したら(下記をご覧下さい)undefを返し、 $DBI::err, $DBI::errstr を設定します ($! は明示的には 設定しません)。 一般的には connect の戻りステータスを確認し、失敗していたら $DBI::errstr を表示します。

Multiple simultaneous connections to multiple databases through multiple drivers can be made via the DBI. Simply make one connect call for each database and keep a copy of each returned database handle.

DBI 経由で、複数のデータベースに対しての複数のドライバを使って、同時に 複数接続することができます。 単純に各データベース毎に connect を呼び出し、返された データベースハンドルのコピーをとっておいてください。

The $data_source value must begin with "dbi:driver_name:". The driver_name specifies the driver that will be used to make the connection. (Letter case is significant.)

$data_source の値は "dbi:ドライバ名:" で 始まらなければなりません。 ドライバ名 が接続ために使われるドライバを示します。 (大文字小文字は区別されます).

As a convenience, if the $data_source parameter is undefined or empty, the DBI will substitute the value of the environment variable DBI_DSN. If just the driver_name part is empty (i.e., the $data_source prefix is "dbi::"), the environment variable DBI_DRIVER is used. If neither variable is set, then connect dies.

便宜上、$data_source フィールドが未定義あるいは空だった場合、DBI は この値を環境変数 DBI_DSN の値で置換します。 ドライバ名の部分だけが空だった場合(つまり $data_source の始まりが "dbi::") 、環境変数 DBI_DRIVER が使われます。 もし変数も設定されていなければ connect は die します。

Examples of $data_source values are:

$data_source の値の例は:

  dbi:DriverName:database_name
  dbi:DriverName:database_name@hostname:port
  dbi:DriverName:database=database_name;host=hostname;port=port

There is no standard for the text following the driver name. Each driver is free to use whatever syntax it wants. The only requirement the DBI makes is that all the information is supplied in a single string. You must consult the documentation for the drivers you are using for a description of the syntax they require.

ドライバ名の後ろにつく文字列については 標準はありません。 各ドライバは欲しい書き方をどんなものでも自由に使うことができます。 DBI が要求するのは、すべての情報が一つの文字列として与えられることだけです。 使っているドライバが要求している書き方の説明の説明については、その ドキュメントを調べなければなりません。

It is recommended that drivers support the ODBC style, shown in the last example above. It is also recommended that that they support the three common names 'host', 'port', and 'database' (plus 'db' as an alias for database). This simplifies automatic construction of basic DSNs: "dbi:$driver:database=$db;host=$host;port=$port". Drivers should aim to 'do something reasonable' when given a DSN in this form, but if any part is meaningless for that driver (such as 'port' for Informix) it should generate an error if that part is not empty.

ドライバは上述の最後の例である ODBC 形式に対応することが推奨されています。 また、三つの共通の名前 'host', 'port', 'database' (および database の別名としての 'db') に対応することも推奨されています。 これにより基本的な DSN の自動的な構築が簡単になります: "dbi:$driver:database=$db;host=$host;port=$port"。 ドライバは、DSN がこの形式で与えられたとき、「何か意味のあることをする」 ことを目指すべきですが、(Infomix にとっての 'port' のように)どれかの部分が このドライバにとって意味がない場合、その部分が空でないときには エラーを発生させるべきです。

If the environment variable DBI_AUTOPROXY is defined (and the driver in $data_source is not "Proxy") then the connect request will automatically be changed to:

環境変数 DBI_AUTOPROXY が定義されていれば(そして $data_source の データソースが "Proxy" でなければ)、接続要求は自動的に以下のように 変更されます:

  $ENV{DBI_AUTOPROXY};dsn=$data_source

DBI_AUTOPROXY is typically set as "dbi:Proxy:hostname=...;port=...". If $ENV{DBI_AUTOPROXY} doesn't begin with 'dbi:' then "dbi:Proxy:" will be prepended to it first. See the DBD::Proxy documentation for more details.

DBI_AUTOPROXY は、通常 "dbi:Proxy:hostname=...;port=..." となります。 $ENV{DBI_AUTOPROXY} が 'dbi:' で始まっていない場合は、先頭に "dbi:Proxy:" を追加します。 詳細については DBD::Proxyドキュメント をご覧ください。

If $username or $password are undefined (rather than just empty), then the DBI will substitute the values of the DBI_USER and DBI_PASS environment variables, respectively. The DBI will warn if the environment variables are not defined. However, the everyday use of these environment variables is not recommended for security reasons. The mechanism is primarily intended to simplify testing. See below for alternative way to specify the username and password.

$username または $password が未定義(あるいは単に空)ならば、 DBI はそれぞれ環境変数 DBI_USERDBI_PASS の値で置き換えます。 その環境変数が定義されてなければ、DBI は警告します。 しかしながら、これらの環境変数を普段使いすることは、セキュリティ上の理由から お勧めしません。 この機能は基本的にテストを簡単にすることを目的としています。 ユーザー名とパスワードを指定するための代替案については後述します。

DBI->connect automatically installs the driver if it has not been installed yet. Driver installation either returns a valid driver handle, or it dies with an error message that includes the string "install_driver" and the underlying problem. So DBI->connect will die on a driver installation failure and will only return undef on a connect failure, in which case $DBI::errstr will hold the error message. Use eval { ... } if you need to catch the "install_driver" error.

DBI->connect は、まだインストールされていないドライバを自動的に インストールします。 ドライバのインストールは適切なドライバハンドルを返すか、 "install_driver" という文字列と基になった問題が入った エラーメッセージとともに die するかのどちらかです。 そのため DBI->connect はドライバインストールの障害のときには die して、接続の障害のときには undef を返すだけです; そのときには $DBI::errstr にエラーの情報が入っています。 "install_driver" エラーを捕捉する必要がある場合は eval { ... } を 使ってください。

The $data_source argument (with the "dbi:...:" prefix removed) and the $username and $password arguments are then passed to the driver for processing. The DBI does not define any interpretation for the contents of these fields. The driver is free to interpret the $data_source, $username, and $password fields in any way, and supply whatever defaults are appropriate for the engine being accessed. (Oracle, for example, uses the ORACLE_SID and TWO_TASK environment variables if no $data_source is specified.)

$data_source 引数 ( "dbi:...:" という接頭辞をとったもの)と $username, $password の引数は、処理のためドライバに渡されます。 DBI はこれらのフィールドの内容の解釈について何も定義していません。 ドライバは $data_source, $username, $password のフィールドを、 どんなふうにも自由に解析することができます。 そしてアクセスされるエンジンに合わせて、いかなるデフォルトも 設定することができます。 (例えば Oracle では、データソースが指定されていなければ、環境変数 ORACLE_SID と TWO_TASK を使います)。

The AutoCommit and PrintError attributes for each connection default to "on". (See "AutoCommit" and "PrintError" for more information.) However, it is strongly recommended that you explicitly define AutoCommit rather than rely on the default. The PrintWarn attribute defaults to on if $^W is true, i.e., perl is running with warnings enabled.

各コネクションの AutoCommitPrintError 属性のデフォルトは "on" です。 (詳細は AutoCommitPrintError をご覧ください)。 しかしながら、デフォルトにまかませるよりも明示的に AutoCommit を 定義することが強く推奨されます。 $^W が真なら PrintWarn 属性のデフォルトはオンです; つまり、perl は 警告を有効にして動作します。

The \%attr parameter can be used to alter the default settings of PrintError, RaiseError, AutoCommit, and other attributes. For example:

\%attr パラメータを使って、PrintError, RaiseError, AutoCommit などの属性のデフォルト値を変更することができます。 例:

  $dbh = DBI->connect($data_source, $user, $pass, {
        PrintError => 0,
        AutoCommit => 0
  });

The username and password can also be specified using the attributes Username and Password, in which case they take precedence over the $username and $password parameters.

ユーザー名とパスワードは属性 UsernamePassword を使っても 指定でき、この場合は $username$password のパラメータより 優先されます。

You can also define connection attribute values within the $data_source parameter. For example:

$data_source パラメータの中で接続属性の値を定義することもできます。 例:

  dbi:DriverName(PrintWarn=>1,PrintError=>0,Taint=>1):...

Individual attributes values specified in this way take precedence over any conflicting values specified via the \%attr parameter to connect.

この方法で指定される各属性値は、connect への \%attr パラメータを 介して指定された値とぶつかっても優先されます。

The dbi_connect_method attribute can be used to specify which driver method should be called to establish the connection. The only useful values are 'connect', 'connect_cached', or some specialized case like 'Apache::DBI::connect' (which is automatically the default when running within Apache).

dbi_connect_method 属性は接続を確立するさいにどちらのドライバメソッドが 呼ばれるべきかを指定するために使われます。 これには 'connect', 'connect_cached', 'Apache::DBI::connect' これは Apache で実行されたときには自動的にデフォルトになります)のような ある特別なケースが使えます。

Where possible, each session ($dbh) is independent from the transactions in other sessions. This is useful when you need to hold cursors open across transactions--for example, if you use one session for your long lifespan cursors (typically read-only) and another for your short update transactions.

可能であれば、各セッション ($dbh) は他のセッションのトランザクションから 独立しています。 これはカーソルをトランザクションをまたがってオープンしたままにする必要がある 場合には便利です。 例えばあるセッションを長い寿命をもつカーソル(通常は読み込み専用)のために使い、 他のセッションで短い更新トランザクションを実行する場合です。

For compatibility with old DBI scripts, the driver can be specified by passing its name as the fourth argument to connect (instead of \%attr):

古い DBI スクリプトとの互換性のために、ドライバの名前を connect の 4 番目の引数として(\%attr の代わりに)、ドライバに指定することができます:

  $dbh = DBI->connect($data_source, $user, $pass, $driver);

In this "old-style" form of connect, the $data_source should not start with "dbi:driver_name:". (If it does, the embedded driver_name will be ignored). Also note that in this older form of connect, the $dbh->{AutoCommit} attribute is undefined, the $dbh->{PrintError} attribute is off, and the old DBI_DBNAME environment variable is checked if DBI_DSN is not defined. Beware that this "old-style" connect will soon be withdrawn in a future version of DBI.

この connect の「旧スタイル」形式では、$data_source は "dbi:ドライバ名:" で始まってはいけません。 (もしそうであれば、埋め込まれたドライバ名は無視されます)。 この古い形式の connectでは、$dbh->{AutoCommit} 属性は未定義、 $dbh->{PrintError} はオフ、そして DBI_DSN が定義されていなければ、 古い DBI_DBNAME 環境変数がチェックされます。 この「旧スタイル」の connect は DBI の近い将来のバージョンで 撤廃されるであろうということに用心してください。

connect_cached

  $dbh = DBI->connect_cached($data_source, $username, $password)
            or die $DBI::errstr;
  $dbh = DBI->connect_cached($data_source, $username, $password, \%attr)
            or die $DBI::errstr;

connect_cached is like "connect", except that the database handle returned is also stored in a hash associated with the given parameters. If another call is made to connect_cached with the same parameter values, then the corresponding cached $dbh will be returned if it is still valid. The cached database handle is replaced with a new connection if it has been disconnected or if the ping method fails.

connect_cached は返されるデータベースハンドルが与えられたパラメータと 関連付けられてハッシュにも格納されるという点を除けば、"connect" に 似ています。 同じパラメータ値で connect_cached がもう一度呼ばれると、それがまだ 適切であれば、キャッシュされた対応する $dbh が返されます。 すでに切断されていたり、ping メソッドが失敗したら、キャッシュされた データベースハンドルは新しい接続で置きかえられます。

Note that the behaviour of this method differs in several respects from the behaviour of persistent connections implemented by Apache::DBI. However, if Apache::DBI is loaded then connect_cached will use it.

このメソッドの動きは、Apache::DBI によって実装されている永続接続の動きとは 多くの点で異なることに注意してください。 しかし、Apache::DBI が読み込まれると、connect_cached はこれを 使います。

Caching connections can be useful in some applications, but it can also cause problems, such as too many connections, and so should be used with care. In particular, avoid changing the attributes of a database handle created via connect_cached() because it will affect other code that may be using the same handle. When connect_cached() returns a handle the attributes will be reset to their initial values. This can cause problems, especially with the AutoCommit attribute.

キャッシュは、あるアプリケーションによっては便利かもしれませんが、 たくさん接続しすぎるといった問題もおこすかもしれませんし、注意して 使わなければなりません。 とくに、connect_cached() で作成したデータベースハンドルの属性を 変えることは避けてください; 同じハンドルを使っている他のコードに 影響を与えることになるからです。 connect_cached() がハンドルを返すとき、属性は初期値にリセットされます。 これは(特に AutoCommit 属性で) 問題になる可能性があります。

Where multiple separate parts of a program are using connect_cached() to connect to the same database with the same (initial) attributes it is a good idea to add a private attribute to the connect_cached() call to effectively limit the scope of the caching. For example:

Where multiple separate parts of a program are using connect_cached() to connect to the same database with the same (initial) attributes it is a good idea to add a private attribute to the connect_cached() call to effectively limit the scope of the caching. 例えば: (TBT)

  DBI->connect_cached(..., { private_foo_cachekey => "Bar", ... });

Handles returned from that connect_cached() call will only be returned by other connect_cached() call elsewhere in the code if those other calls also pass in the same attribute values, including the private one. (I've used private_foo_cachekey here as an example, you can use any attribute name with a private_ prefix.)

Handles returned from that connect_cached() call will only be returned by other connect_cached() call elsewhere in the code if those other calls also pass in the same attribute values, including the private one. (私はここで例として private_foo_cachekey を使っていますが、 private_ 接頭辞を保つどのような属性めいでも使えます。) (TBT)

Taking that one step further, you can limit a particular connect_cached() call to return handles unique to that one place in the code by setting the private attribute to a unique value for that place:

Taking that one step further, you can limit a particular connect_cached() call to return handles unique to that one place in the code by setting the private attribute to a unique value for that place: (TBT)

  DBI->connect_cached(..., { private_foo_cachekey => __FILE__.__LINE__, ... });

By using a private attribute you still get connection caching for the individual calls to connect_cached() but, by making separate database connections for separate parts of the code, the database handles are isolated from any attribute changes made to other handles.

By using a private attribute you still get connection caching for the individual calls to connect_cached() but, by making separate database connections for separate parts of the code, the database handles are isolated from any attribute changes made to other handles. (TBT)

The cache can be accessed (and cleared) via the "CachedKids" attribute:

キャッシュは "CachedKids" 属性を介してアクセス(そしてクリア)することが できます:

  my $CachedKids_hashref = $dbh->{Driver}->{CachedKids};
  %$CachedKids_hashref = () if $CachedKids_hashref;

available_drivers

  @ary = DBI->available_drivers;
  @ary = DBI->available_drivers($quiet);

Returns a list of all available drivers by searching for DBD::* modules through the directories in @INC. By default, a warning is given if some drivers are hidden by others of the same name in earlier directories. Passing a true value for $quiet will inhibit the warning.

@INC のディレクトリから DBD::* モジュールを検索して、使用可能な ドライバのリストを返します。 デフォルトでは、先に見つかったディレクトリにある同じ名前のものにより、 隠されてしまうドライバがあれば警告します。 警告を抑止するには $quiet を真の値にします。

installed_drivers

  %drivers = DBI->installed_drivers();

Returns a list of driver name and driver handle pairs for all drivers 'installed' (loaded) into the current process. The driver name does not include the 'DBD::' prefix.

現在のプロセスに「インストールされた」(読み込まれた)全てのドライバの ドライバ名とドライバハンドルの組のリストを返します。 ドライバ名には 'DBD::' 接頭辞は付いていません。

To get a list of all drivers available in your perl installation you can use "available_drivers".

インストールされている perl で利用可能な全てのドライバのリストを得るには、 "available_drivers" が使えます。

Added in DBI 1.49.

DBI 1.49 で追加されました。

installed_versions

  DBI->installed_versions;
  @ary  = DBI->installed_versions;
  %hash = DBI->installed_versions;

Calls available_drivers() and attempts to load each of them in turn using install_driver(). For each load that succeeds the driver name and version number are added to a hash. When running under DBI::PurePerl drivers which appear not be pure-perl are ignored.

available_drivers() を呼び出して、そのそれぞれに対して install_driver() を 使って読み込もうとします。 読み込みに成功したドライバの名前とバージョン番号はハッシュに追加されます。 DBI::PurePerl ドライバで実行するとピュア perl でないように見える ドライバは無視されます。

When called in array context the list of successfully loaded drivers is returned (without the 'DBD::' prefix).

配列コンテキストで呼び出されると、読み込みに成功したドライバのリストが ('DBD::' の接頭辞なしで) 返されます。

When called in scalar context a reference to the hash is returned and the hash will also contain other entries for the DBI version, OS name, etc.

スカラコンテキストで呼び出されると、ハッシュへのリファレンスが返され、 このハッシュには DBI バージョン、OS 名などのその他のエントリも 含まれます。

When called in a void context the installed_versions() method will print out a formatted list of the hash contents, one per line.

無効コンテキストで呼び出されると、installed_versions() メソッドは ハッシュの内容を行単位でフォーマットしたリストを出力します。

Due to the potentially high memory cost and unknown risks of loading in an unknown number of drivers that just happen to be installed on the system, this method is not recommended for general use. Use available_drivers() instead.

潜在的にメモリコストが高いことと、何個か分からないシステムに インストールされているドライバを読み込むという不明なリスクがあるので、 このメソッドは一般的な使用は推奨されません。 代わりに available_drivers() を使ってください。

The installed_versions() method is primarily intended as a quick way to see from the command line what's installed. For example:

installed_versions() メソッドは主としてインストールされているものを コマンドラインから素早く見ることを目的としています。 例えば:

  perl -MDBI -e 'DBI->installed_versions'

The installed_versions() method was added in DBI 1.38.

installed_versions() メソッドは DBI 1.38 で追加されました。

data_sources

  @ary = DBI->data_sources($driver);
  @ary = DBI->data_sources($driver, \%attr);

Returns a list of data sources (databases) available via the named driver. If $driver is empty or undef, then the value of the DBI_DRIVER environment variable is used.

指定された名前のドライバで使うことができるデータソース(データベース)の リストを返します。 $driver が空もしくは undef であれば、環境変数 DBI_DRIVER の値が 使われます。

The driver will be loaded if it hasn't been already. Note that if the driver loading fails then data_sources() dies with an error message that includes the string "install_driver" and the underlying problem.

まだロードされていなければ、ドライバはロードされます。 もしドライバのローディングが失敗したら、"install_driver" という文字列と そこにある問題が入ったエラーメッセージで die することに注意してください。

Data sources are returned in a form suitable for passing to the "connect" method (that is, they will include the "dbi:$driver:" prefix).

データソースは "connect" メソッドに渡すのに適したな形式で返されます。 (つまり接頭辞 "dbi:$driver:" が入ります。)

Note that many drivers have no way of knowing what data sources might be available for it. These drivers return an empty or incomplete list or may require driver-specific attributes.

多くのドライバが利用できるデータソースを調べる方法を 持っていないということに注意してください。 これらのドライバは空もしくは不完全なリストが返したり、 あるいはドライバ特有の属性が与えられることを必要とするかもしれません。

There is also a data_sources() method defined for database handles.

データベースハンドルのために定義されている data_sources() メソッドも あります。

trace

  DBI->trace($trace_setting)
  DBI->trace($trace_setting, $trace_filename)
  DBI->trace($trace_setting, $trace_filehandle)
  $trace_setting = DBI->trace;

The DBI->trace method sets the global default trace settings and returns the previous trace settings. It can also be used to change where the trace output is sent.

DBI->trace メソッドは グローバルにデフォルトの トレース設定を セットし、以前の トレース設定を返します。 これはまた、トレース出力をどこに送るかを変更するためにも使います。

There's a similar method, $h->trace, which sets the trace settings for the specific handle it's called on.

似たようなメソッドして $h->trace があり、これは呼び出された 特定のハンドルのトレース設定を設定します。

See the "TRACING" section for full details about the DBI's powerful tracing facilities.

DBI の強力なトレース機能に関する完全な詳細については "TRACING" の章を参照してください。

visit_handles

  DBI->visit_handles( $coderef );
  DBI->visit_handles( $coderef, $info );

Where $coderef is a reference to a subroutine and $info is an arbitrary value which, if undefined, defaults to a reference to an empty hash. Returns $info.

$coderef はサブルーチンへのリファレンスで、$info は任意の値であり、 もし未定義ならデフォルトはからハッシュへのリファレンスとなります。 $info を返します。

For each installed driver handle, if any, $coderef is invoked as:

インストールされているドライバがあれば、そのハンドル毎に、 $coderef は以下のようにして起動されます:

  $coderef->($driver_handle, $info);

If the execution of $coderef returns a true value then "visit_child_handles" is called on that child handle and passed the returned value as $info.

$coderef の実行によって真の値が返されると、"visit_child_handles" が 子ハンドルに呼び出され、返された値を $info として渡します。

For example:

例えば:

  my $info = $dbh->{Driver}->visit_child_handles(sub {
      my ($h, $info) = @_;
      ++$info->{ $h->{Type} }; # count types of handles (dr/db/st)
      return $info; # visit kids
  });

"visit_child_handles" も参照してください。

DBI ユーティリティ関数

In addition to the DBI methods listed in the previous section, the DBI package also provides several utility functions.

前のセクションで一覧ししたメソッドに加えて、DBIパッケージはいくつかの ユーティリティ関数も提供しています。

These can be imported into your code by listing them in the use statement. For example:

これらは use 文でリストすることであなたのコードにインポートできます。 例えば:

  use DBI qw(neat data_diff);

Alternatively, all these utility functions (except hash) can be imported using the :utils import tag. For example:

あるいは、(hash を除く)これらのユーティリティ関す全てを :utils インポートタグを使ってインポートできます。 例えば:

  use DBI qw(:utils);

data_string_desc

  $description = data_string_desc($string);

Returns an informal description of the string. For example:

文字列に関する略式の記述を返します。 例えば:

  UTF8 off, ASCII, 42 characters 42 bytes
  UTF8 off, non-ASCII, 42 characters 42 bytes
  UTF8 on, non-ASCII, 4 characters 6 bytes
  UTF8 on but INVALID encoding, non-ASCII, 4 characters 6 bytes
  UTF8 off, undef

The initial UTF8 on/off refers to Perl's internal SvUTF8 flag. If $string has the SvUTF8 flag set but the sequence of bytes it contains are not a valid UTF-8 encoding then data_string_desc() will report UTF8 on but INVALID encoding.

最初の UTF8 on/off は Perl 内部の SvUTF8 フラグを参照します。 $string に SvUTF8 フラグがセットされているけれどもその内容が有効な UTF-8 エンコーディングでない場合、data_string_desc() は UTF8 on but INVALID encoding と報告します。

The ASCII vs non-ASCII portion shows ASCII if all the characters in the string are ASCII (have code points <= 127).

ASCIInon-ASCII の部分は、文字列の 全ての 文字が ASCII (文字位置が <= 127) なら ASCII となります。

The data_string_desc() function was added in DBI 1.46.

data_string_desc() 関数は DBI 1.46 で追加されました。

data_string_diff

  $diff = data_string_diff($a, $b);

Returns an informal description of the first character difference between the strings. If both $a and $b contain the same sequence of characters then data_string_diff() returns an empty string. For example:

二つの文字列の間で最初に異なる文字の非公式な説明を返します。 $a と $b が同じ文字並びなら、data_string_diff() は空文字列を返します。 例えば:

 Params a & b     Result
 ------------     ------
 'aaa', 'aaa'     ''
 'aaa', 'abc'     'Strings differ at index 2: a[2]=a, b[2]=b'
 'aaa', undef     'String b is undef, string a has 3 characters'
 'aaa', 'aa'      'String b truncated after 2 characters'

Unicode characters are reported in \x{XXXX} format. Unicode code points in the range U+0800 to U+08FF are unassigned and most likely to occur due to double-encoding. Characters in this range are reported as \x{08XX}='C' where C is the corresponding latin-1 character.

Unicode 文字は \x{XXXX} 形式で報告されます。 U+0800 から U+08FF の範囲の Unicode 符号位置は未定義で、もっとも ありそうなことは二重エンコーディングです。 この範囲の文字は \x{08XX}='C' として報告されます; ここで C は対応する latin-1 文字です。

The data_string_diff() function only considers logical characters and not the underlying encoding. See "data_diff" for an alternative.

data_string_diff() 関数は、論理的な 文字 だけを考慮し、その 基礎となるエンコーディングは考慮しません。 代替案に関しては "data_diff" を参照してください。

The data_string_diff() function was added in DBI 1.46.

data_string_diff() 関数は DBI 1.46 で追加されました。

data_diff

  $diff = data_diff($a, $b);
  $diff = data_diff($a, $b, $logical);

Returns an informal description of the difference between two strings. It calls "data_string_desc" and "data_string_diff" and returns the combined results as a multi-line string.

二つの文字列の違いに関する非公式な説明を返します。 これは "data_string_desc""data_string_diff" を呼び出し、 結合した結果を複数行の文字列として返します。

For example, data_diff("abc", "ab\x{263a}") will return:

例えば、data_diff("abc", "ab\x{263a}") は以下のものを返します:

  a: UTF8 off, ASCII, 3 characters 3 bytes
  b: UTF8 on, non-ASCII, 3 characters 5 bytes
  Strings differ at index 2: a[2]=c, b[2]=\x{263A}

If $a and $b are identical in both the characters they contain and their physical encoding then data_diff() returns an empty string. If $logical is true then physical encoding differences are ignored (but are still reported if there is a difference in the characters).

If $a and $b are identical in both the characters they contain and their physical encoding then data_diff() returns an empty string. $logical が新なら物理的なエンコーディングの違いは無視されます (しかし文字に違いがあればやはり報告されます)。 (TBT)

The data_diff() function was added in DBI 1.46.

data_diff() 関数は DBI 1.46 で追加されました。

neat

  $str = neat($value);
  $str = neat($value, $maxlen);

Return a string containing a neat (and tidy) representation of the supplied value.

与えられた文字列を整然と(そしてきれいに)整えられた文字列を返します。

Strings will be quoted, although internal quotes will not be escaped. Values known to be numeric will be unquoted. Undefined (NULL) values will be shown as undef (without quotes).

文字列はクォーテーションで囲まれますが、文字列の中のクォーテーションは エスケープ されません。 数値であるとわかっている値はクォーテーションで囲まれません。 未定義(NULL) 値は(クォートなしで)undef で表されます。

If the string is flagged internally as utf8 then double quotes will be used, otherwise single quotes are used and unprintable characters will be replaced by dot (.).

文字列が内部で UTF8 として記録されていると、ダブルクォートが使われ、 さもなければシングルクォートが使われ、表示できない文字は点(.)で 置き換えられます。

For result strings longer than $maxlen the result string will be truncated to $maxlen-4 and "...'" will be appended. If $maxlen is 0 or undef, it defaults to $DBI::neat_maxlen which, in turn, defaults to 400.

変換結果の文字列が $masxlen よりも長ければ、文字列は $maxlen-4 の 長さに切り詰め、"...'" が後ろにつけられます。 $maxlen が 0 または undef であれば、$DBI::neat_maxlen (デフォルトは400)が代りにデフォルトになります。

This function is designed to format values for human consumption. It is used internally by the DBI for "trace" output. It should typically not be used for formatting values for database use. (See also "quote".)

この関数は人の目にわかりやすいように値の形式を整えるように考えられています。 これは DBI 内部で "trace" 出力に使われています。 通常データベースが利用するよう、値の形を整えるために使っては いけません ("quote" もご覧ください)。

neat_list

  $str = neat_list(\@listref, $maxlen, $field_sep);

Calls neat on each element of the list and returns a string containing the results joined with $field_sep. $field_sep defaults to ", ".

リストの各要素に neat を呼び出し、その結果を $field_sep でつなげた 結果の文字列を返します。 $field_sep のデフォルトは ", " です。

looks_like_number

  @bool = looks_like_number(@array);

Returns true for each element that looks like a number. Returns false for each element that does not look like a number. Returns undef for each element that is undefined or empty.

リストの各要素について数値に見えば真を返します。 各要素が数値に見えなければ偽を返します。 各要素が未定義あるいは空であれば、undef もしくは空を返します。

hash

  $hash_value = DBI::hash($buffer, $type);

Return a 32-bit integer 'hash' value corresponding to the contents of $buffer. The $type parameter selects which kind of hash algorithm should be used.

$buffer の内容に対応する 32 ビット整数の「ハッシュ」値を返します。 $type パラメータは使用するハッシュアルゴリズムを選択します。

For the technically curious, type 0 (which is the default if $type isn't specified) is based on the Perl 5.1 hash except that the value is forced to be negative (for obscure historical reasons). Type 1 is the better "Fowler / Noll / Vo" (FNV) hash. See http://www.isthe.com/chongo/tech/comp/fnv/ for more information. Both types are implemented in C and are very fast.

技術的好奇心のために、型 0 (これは $type が指定されなかったときの デフォルトです) は Perl 5.1 ハッシュを基にしていますが、(はっきりしない 歴史的な理由により) 値は負数に制限されます。 型 1 はよりより "Fowler / Noll / Vo" (FNV) ハッシュです。 さらなる情報については http://www.isthe.com/chongo/tech/comp/fnv/ を 参照してください。 どちらの型も C で実装されていてとても速いです。

This function doesn't have much to do with databases, except that it can be handy to store hash values in a database.

この関数はデータベースに対して何かをするというものではありませんが、 データベースにハッシュ値を補完するのに便利です。

sql_type_cast

  $sts = DBI->sql_type_cast($sv, $sql_type, $flags);

sql_type_cast attempts to cast $sv to the SQL type (see "DBI Constants") specified in $sql_type. At present only the SQL types SQL_INTEGER, SQL_DOUBLE and SQL_NUMERIC are supported.

sql_type_cast attempts to cast $sv to the SQL type (see "DBI Constants") specified in $sql_type. At present only the SQL types SQL_INTEGER, SQL_DOUBLE and SQL_NUMERIC are supported. (TBT)

For SQL_INTEGER the effect is similar to using the value in an expression that requires an integer. It gives the perl scalar an 'integer aspect'. (Technically the value gains an IV, or possibly a UV or NV if the value is too large for an IV.)

For SQL_INTEGER the effect is similar to using the value in an expression that requires an integer. It gives the perl scalar an 'integer aspect'. (Technically the value gains an IV, or possibly a UV or NV if the value is too large for an IV.) (TBT)

For SQL_DOUBLE the effect is similar to using the value in an expression that requires a general numeric value. It gives the perl scalar a 'numeric aspect'. (Technically the value gains an NV.)

For SQL_DOUBLE the effect is similar to using the value in an expression that requires a general numeric value. It gives the perl scalar a 'numeric aspect'. (Technically the value gains an NV.) (TBT)

SQL_NUMERIC is similar to SQL_INTEGER or SQL_DOUBLE but more general and more cautious. It will look at the string first and if it looks like an integer (that will fit in an IV or UV) it will act like SQL_INTEGER, if it looks like a floating point value it will act like SQL_DOUBLE, if it looks like neither then it will do nothing - and thereby avoid the warnings that would be generated by SQL_INTEGER and SQL_DOUBLE when given non-numeric data.

SQL_NUMERIC is similar to SQL_INTEGER or SQL_DOUBLE but more general and more cautious. It will look at the string first and if it looks like an integer (that will fit in an IV or UV) it will act like SQL_INTEGER, if it looks like a floating point value it will act like SQL_DOUBLE, if it looks like neither then it will do nothing - and thereby avoid the warnings that would be generated by SQL_INTEGER and SQL_DOUBLE when given non-numeric data. (TBT)

$flags may be:

$flags は:

DBIstcf_DISCARD_STRING

If this flag is specified then when the driver successfully casts the bound perl scalar to a non-string type then the string portion of the scalar will be discarded.

If this flag is specified then when the driver successfully casts the bound perl scalar to a non-string type then the string portion of the scalar will be discarded. (TBT)

DBIstcf_STRICT

If $sv cannot be cast to the requested $sql_type then by default it is left untouched and no error is generated. If you specify DBIstcf_STRICT and the cast fails, this will generate an error.

If $sv cannot be cast to the requested $sql_type then by default it is left untouched and no error is generated. If you specify DBIstcf_STRICT and the cast fails, this will generate an error. (TBT)

The returned $sts value is:

返された $sts の値は:

  -2 sql_type is not handled
  -1 sv is undef so unchanged
   0 sv could not be cast cleanly and DBIstcf_STRICT was used
   1 sv could not be case and DBIstcf_STRICT was not used
   2 sv was cast successfully

This method is exported by the :utils tag and was introduced in DBI 1.611.

このメソッドは :utils タグでエクスポートされ、DBI 1.611 で 導入されました。

DBI 動的属性

Dynamic attributes are always associated with the last handle used (that handle is represented by $h in the descriptions below).

動的属性は 最後に使われたハンドル に関連づけられます。 (そのハンドルは以下の説明では $h で示されます)

Where an attribute is equivalent to a method call, then refer to the method call for all related documentation.

属性がメソッド呼び出しと同様のところでは、すべての関連する ドキュメンテーションでそのメソッド呼び出しを参照してください。

Warning: these attributes are provided as a convenience but they do have limitations. Specifically, they have a short lifespan: because they are associated with the last handle used, they should only be used immediately after calling the method that "sets" them. If in any doubt, use the corresponding method call.

警告: 便宜上、これらの属性を用意していますが、限界があります。 特にこれらの有効な時間は長くありません: 最後に使われたハンドルに 関連付けられているために、それらを「設定した」メソッドを呼び出した すぐ後 にしか使うことができません。 少しでも疑問があれば、対応するメソッド呼び出しを使ってください。

$DBI::err

Equivalent to $h->err.

$h->err と等価です。

$DBI::errstr

Equivalent to $h->errstr.

$h->errstr と等価です。

$DBI::state

Equivalent to $h->state.

$h->state と等価です。

$DBI::rows

Equivalent to $h->rows. Please refer to the documentation for the "rows" method.

$h->rows と等価です。 "rows" メソッドの文書を参照してください。

$DBI::lasth

Returns the DBI object handle used for the most recent DBI method call. If the last DBI method call was a DESTROY then $DBI::lasth will return the handle of the parent of the destroyed handle, if there is one.

最後の DBI メソッド呼び出しに使われた DBI オブジェクトハンドルを返します。 最後の DBI メソッド呼び出しが DESTROY であれば、$DBI::lasth はもしあれば、 破壊されたハンドルの親のハンドルを返します。

全てのハンドルに共通のメソッド

The following methods can be used by all types of DBI handles.

以下のメソッドは DBI ハンドルのすべてのタイプに使うことができます。

err

  $rv = $h->err;

Returns the native database engine error code from the last driver method called. The code is typically an integer but you should not assume that.

最後のドライバ関数呼び出しについて ネイティブ なデータベースエンジン エラーコードを返します。 コードは典型的には整数ですが、それを想定するべきではありません。

The DBI resets $h->err to undef before almost all DBI method calls, so the value only has a short lifespan. Also, for most drivers, the statement handles share the same error variable as the parent database handle, so calling a method on one handle may reset the error on the related handles.

DBI はほとんど全ての DBI メソッドを呼び出す前に $h->err を undef に リセットするので、この値は短い間だけ有効です。 またほとんどのドライバでは、文ハンドルは同じエラー変数を 親データベースハンドルと共有するので、あるハンドルに対してメソッドを呼び出すと、 関連するtハンドルのエラーをリセットするかもしれません。

(Methods which don't reset err before being called include err() and errstr(), obviously, state(), rows(), func(), trace(), trace_msg(), ping(), and the tied hash attribute FETCH() and STORE() methods.)

(Methods which don't reset err before being called include err() and errstr(), obviously, state(), rows(), func(), trace(), trace_msg(), ping(), and the tied hash attribute FETCH() and STORE() methods.) (TBT)

If you need to test for specific error conditions and have your program be portable to different database engines, then you'll need to determine what the corresponding error codes are for all those engines and test for all of them.

特定のエラー状況についてテストする必要があり、かつ あなたのプログラムが 他のデータベース・エンジンに対して移植可能にする必要があれば、それら すべてのエンジンについて対応するエラーコードが何かを判定し、それらの すべてについてテストする必要があります。

The DBI uses the value of $DBI::stderr as the err value for internal errors. Drivers should also do likewise. The default value for $DBI::stderr is 2000000000.

DBI は $DBI::stderr の値を、内部エラーのための err 値として使います。 ドライバも似たようなことをします。 $DBI::stderr のデフォルト値は 2000000000 です。

A driver may return 0 from err() to indicate a warning condition after a method call. Similarly, a driver may return an empty string to indicate a 'success with information' condition. In both these cases the value is false but not undef. The errstr() and state() methods may be used to retrieve extra information in these cases.

A driver may return 0 from err() to indicate a warning condition after a method call. Similarly, a driver may return an empty string to indicate a 'success with information' condition. In both these cases the value is false but not undef. The errstr() and state() methods may be used to retrieve extra information in these cases. (TBT)

See "set_err" for more information.

さらなる情報については "set_err" を参照してください。

errstr

  $str = $h->errstr;

Returns the native database engine error message from the last DBI method called. This has the same lifespan issues as the "err" method described above.

最後の DBI 関数呼び出しについて、ネイティブなデータベースエンジンエラーメッセージを返します。 上記で説明した "err" メソッドと同じ有効期間の問題を持っています。

The returned string may contain multiple messages separated by newline characters.

返された文字列は改行文字で区切られた複数のメッセージを 含んでいるかもしれません。

The errstr() method should not be used to test for errors, use err() for that, because drivers may return 'success with information' or warning messages via errstr() for methods that have not 'failed'.

The errstr() method should not be used to test for errors, use err() for that, because drivers may return 'success with information' or warning messages via errstr() for methods that have not 'failed'. (TBT)

See "set_err" for more information.

さらなる情報については "set_err" を参照してください。

state

  $str = $h->state;

Returns a state code in the standard SQLSTATE five character format. Note that the specific success code 00000 is translated to any empty string (false). If the driver does not support SQLSTATE (and most don't), then state() will return S1000 (General Error) for all errors.

エラーコードを標準の SQLSTATE の 5 文字形式で返します。 ある正常コード 00000 は、空文字列(偽)に変換されてしまうことに 注意してください。 もしドライバが SQLSTATE に対応していなければ(ほとんどが 対応していないのですが)、state() はすべてのエラーについて S1000(一般エラー)を返します。

The driver is free to return any value via state, e.g., warning codes, even if it has not declared an error by returning a true value via the "err" method described above.

ドライバは state でどのような値を返すことも自由です; 例えば 警告コード; 上記の "err" メソッドを介して真の値を返すことにより 宣言されるエラーでなかったとしても。

The state() method should not be used to test for errors, use err() for that, because drivers may return a 'success with information' or warning state code via state() for methods that have not 'failed'.

The state() method should not be used to test for errors, use err() for that, because drivers may return a 'success with information' or warning state code via state() for methods that have not 'failed'. (TBT)

set_err

  $rv = $h->set_err($err, $errstr);
  $rv = $h->set_err($err, $errstr, $state);
  $rv = $h->set_err($err, $errstr, $state, $method);
  $rv = $h->set_err($err, $errstr, $state, $method, $rv);

Set the err, errstr, and state values for the handle. This method is typically only used by DBI drivers and DBI subclasses.

ハンドルのための err, errstr, state の値を設定します。 このメソッドは典型的には DBI ドライバと DBI サブクラスでのみ使用されます。

If the "HandleSetErr" attribute holds a reference to a subroutine it is called first. The subroutine can alter the $err, $errstr, $state, and $method values. See "HandleSetErr" for full details. If the subroutine returns a true value then the handle err, errstr, and state values are not altered and set_err() returns an empty list (it normally returns $rv which defaults to undef, see below).

If the "HandleSetErr" attribute holds a reference to a subroutine it is called first. The subroutine can alter the $err, $errstr, $state, and $method values. See "HandleSetErr" for full details. If the subroutine returns a true value then the handle err, errstr, and state values are not altered and set_err() returns an empty list (it normally returns $rv which defaults to undef, see below). (TBT)

Setting err to a true value indicates an error and will trigger the normal DBI error handling mechanisms, such as RaiseError and HandleError, if they are enabled, when execution returns from the DBI back to the application.

Setting err to a true value indicates an error and will trigger the normal DBI error handling mechanisms, such as RaiseError and HandleError, if they are enabled, when execution returns from the DBI back to the application. (TBT)

Setting err to "" indicates an 'information' state, and setting it to "0" indicates a 'warning' state. Setting err to undef also sets errstr to undef, and state to "", irrespective of the values of the $errstr and $state parameters.

Setting err to "" indicates an 'information' state, and setting it to "0" indicates a 'warning' state. Setting err to undef also sets errstr to undef, and state to "", irrespective of the values of the $errstr and $state parameters. (TBT)

The $method parameter provides an alternate method name for the RaiseError/PrintError/PrintWarn error string instead of the fairly unhelpful 'set_err'.

The $method parameter provides an alternate method name for the RaiseError/PrintError/PrintWarn error string instead of the fairly unhelpful 'set_err'. (TBT)

The set_err method normally returns undef. The $rv parameter provides an alternate return value.

set_err メソッドは普通は undef を返します。 $rv パラメータは代替となる返り値を提供します。

Some special rules apply if the err or errstr values for the handle are already set...

ハンドルのための errerrstr の値が 既に 設定されている場合は、 いくつかの特別ルールが適用されます…

If errstr is true then: " [err was %s now %s]" is appended if $err is true and err is already true and the new err value differs from the original one. Similarly " [state was %s now %s]" is appended if $state is true and state is already true and the new state value differs from the original one. Finally "\n" and the new $errstr are appended if $errstr differs from the existing errstr value. Obviously the %s's above are replaced by the corresponding values.

If errstr is true then: " [err was %s now %s]" is appended if $err is true and err is already true and the new err value differs from the original one. Similarly " [state was %s now %s]" is appended if $state is true and state is already true and the new state value differs from the original one. Finally "\n" and the new $errstr are appended if $errstr differs from the existing errstr value. Obviously the %s's above are replaced by the corresponding values. (TBT)

The handle err value is set to $err if: $err is true; or handle err value is undef; or $err is defined and the length is greater than the handle err length. The effect is that an 'information' state only overrides undef; a 'warning' overrides undef or 'information', and an 'error' state overrides anything.

The handle err value is set to $err if: $err is true; or handle err value is undef; or $err is defined and the length is greater than the handle err length. The effect is that an 'information' state only overrides undef; a 'warning' overrides undef or 'information', and an 'error' state overrides anything. (TBT)

The handle state value is set to $state if $state is true and the handle err value was set (by the rules above).

$state が真でハンドルの err 値が (上述のルールにより) 設定されているなら、ハンドルの state の値は $state に設定されます。

Support for warning and information states was added in DBI 1.41.

警告と情報状態の対応は DBI 1.41 で追加されました。

trace

  $h->trace($trace_settings);
  $h->trace($trace_settings, $trace_filename);
  $trace_settings = $h->trace;

The trace() method is used to alter the trace settings for a handle (and any future children of that handle). It can also be used to change where the trace output is sent.

The trace() method is used to alter the trace settings for a handle (and any future children of that handle). It can also be used to change where the trace output is sent. (TBT)

There's a similar method, DBI->trace, which sets the global default trace settings.

似たようなメソッドとして DBI->trace があり、これはグローバルな デフォルトトレース設定を設定します。

See the "TRACING" section for full details about the DBI's powerful tracing facilities.

DBI の強力なトレース機能に関する完全な詳細については "TRACING" の章を参照してください。

trace_msg

  $h->trace_msg($message_text);
  $h->trace_msg($message_text, $min_level);

Writes $message_text to the trace file if the trace level is greater than or equal to $min_level (which defaults to 1). Can also be called as DBI->trace_msg($msg).

トレースレベルが $min_level (デフォルトは 1)以上の場合の場合、 $message_text をトレースファイルに書き出します。 DBI->trace_msg($msg) と呼び出すこともできます。

See "TRACING" for more details.

さらなる情報については "TRACING" を参照してください。

func

  $h->func(@func_arguments, $func_name) or die ...;

The func method can be used to call private non-standard and non-portable methods implemented by the driver. Note that the function name is given as the last argument.

func メソッドにより、ドライバが実装しているプライベートな標準でなく、 移植できないメソッドを呼び出すことができます。 関数名が 最後の 引数で与えられることに注意してください。

It's also important to note that the func() method does not clear a previous error ($DBI::err etc.) and it does not trigger automatic error detection (RaiseError etc.) so you must check the return status and/or $h->err to detect errors.

It's also important to note that the func() method does not clear a previous error ($DBI::err etc.) and it does not trigger automatic error detection (RaiseError etc.) so you must check the return status and/or $h->err to detect errors. (TBT)

(This method is not directly related to calling stored procedures. Calling stored procedures is currently not defined by the DBI. Some drivers, such as DBD::Oracle, support it in non-portable ways. See driver documentation for more details.)

(このメソッドはストアドプロシージャの呼び出しに、直接は関係していません。 ストアドプロシージャ呼び出しは、いまのところ DBI によって定義されていません。 DBD::Oracle のようにいくつかのドライバが移植できない形でサポートしています。 詳細についてはドライバのドキュメントをご覧ください。)

See also install_method() in DBI::DBD for how you can avoid needing to use func() and gain direct access to driver-private methods.

func() の使用を避けて、ドライバ固有のメソッドに直接アクセスする 方法については DBI::DBD の install_method() も参照してください。

can

  $is_implemented = $h->can($method_name);

Returns true if $method_name is implemented by the driver or a default method is provided by the DBI. It returns false where a driver hasn't implemented a method and the default method is provided by the DBI is just an empty stub.

$method_name がドライバによって実装されているか、デフォルトメソッドが DBI によって提供されているなら真を返します。 ドライバがこのメソッドを実装しておらず、DBI によって提供されている デフォルトメソッドが空のスタブである場合は偽を返します。

parse_trace_flags

  $trace_settings_integer = $h->parse_trace_flags($trace_settings);

Parses a string containing trace settings and returns the corresponding integer value used internally by the DBI and drivers.

トレース設定を含む文字列をパースして、DBI とドライバで内部で使用されている 対応する整数値を返します。

The $trace_settings argument is a string containing a trace level between 0 and 15 and/or trace flag names separated by vertical bar ("|") or comma (",") characters. For example: "SQL|3|foo".

$trace_settings 引数は縦棒 ("|") またはカンマ (",") 文字で区切られた、 0 から 15 のトレースレベルやトレースフラグ名からなる文字列です。 例: "SQL|3|foo"

It uses the parse_trace_flag() method, described below, to process the individual trace flag names.

これは個々のトレースフラグ名を処理するために後述する parse_trace_flag() メソッドを使います。

The parse_trace_flags() method was added in DBI 1.42.

parse_trace_flags() メソッドは DBI 1.42 で追加されました。

parse_trace_flag

  $bit_flag = $h->parse_trace_flag($trace_flag_name);

Returns the bit flag corresponding to the trace flag name in $trace_flag_name. Drivers are expected to override this method and check if $trace_flag_name is a driver specific trace flags and, if not, then call the DBI's default parse_trace_flag().

$trace_flag_name のトレースフラグ名に対応するビットフラグを返します。 ドライバはこのメソッドをオーバーライドして、$trace_flag_name が ドライバ固有のフラグかどうかをチェックし、そうでなければ DBI の デフォルトの parse_trace_flag() を呼び出すことを想定されています。

The parse_trace_flag() method was added in DBI 1.42.

parse_trace_flag() メソッドは DBI 1.42 で追加されました。

private_attribute_info

  $hash_ref = $h->private_attribute_info();

Returns a reference to a hash whose keys are the names of driver-private handle attributes available for the kind of handle (driver, database, statement) that the method was called on.

メソッドが呼び出されたハンドルの種類(ドライバ、データベース、文)で 利用可能なドライバ固有のハンドル属性の名前をキーとしたハッシュへの リファレンスを返します。

For example, the return value when called with a DBD::Sybase $dbh could look like this:

例えば、DBD::Sybase $dbh で呼び出したときの返り値は以下のようになります:

  {
      syb_dynamic_supported => undef,
      syb_oc_version => undef,
      syb_server_version => undef,
      syb_server_version_string => undef,
  }

and when called with a DBD::Sybase $sth they could look like this:

そして DBD::Sybase $sth で呼び出したときは以下のようになります:

  {
      syb_types => undef,
      syb_proc_status => undef,
      syb_result_type => undef,
  }

The values should be undef. Meanings may be assigned to particular values in future.

値は undef であるべきです。 将来特定の値に関する割り当てが行われます。

swap_inner_handle

  $rc = $h1->swap_inner_handle( $h2 );
  $rc = $h1->swap_inner_handle( $h2, $allow_reparent );

Brain transplants for handles. You don't need to know about this unless you want to become a handle surgeon.

ハンドルの脳移植です。 ハンドルの外科医になろうと思っているのでない限りこれについて知る 必要はありません。

A DBI handle is a reference to a tied hash. A tied hash has an inner hash that actually holds the contents. The swap_inner_handle() method swaps the inner hashes between two handles. The $h1 and $h2 handles still point to the same tied hashes, but what those hashes are tied to has been swapped. In effect $h1 becomes $h2 and vice-versa. This is powerful stuff, expect problems. Use with care.

DBI ハンドルは tie されたハッシュへのリファレンスです。 tie されたハッシュは実際に内容を保持している 内部 ハッシュを持っています。 swap_inner_handle() メソッドは二つのハンドルの内部ハッシュを入れ替えます。 $h1 と $h2 のハンドルは同じ tie されたハッシュを示したままですが、 どのハッシュに tie しているかは入れ替わります。 事実上 $h1 は $h2 に なり、逆もまた真なりです。 これは問題もはらんでいる、強力な機能です。 注意して使ってください。

As a small safety measure, the two handles, $h1 and $h2, have to share the same parent unless $allow_reparent is true.

小さな安全性の尺度として、二つのハンドル $h1 と $h2 は、 $allow_reparent が真でない限り同じ親を共有している必要があります。

The swap_inner_handle() method was added in DBI 1.44.

swap_inner_handle() メソッドは DBI 1.44 で追加されました。

Here's a quick kind of 'diagram' as a worked example to help think about what's happening:

以下は、何が起きているかについて考える助けとなる動作する例の 「ダイアグラム」です:

    Original state:
            dbh1o -> dbh1i
            sthAo -> sthAi(dbh1i)
            dbh2o -> dbh2i

    swap_inner_handle dbh1o with dbh2o:
            dbh2o -> dbh1i
            sthAo -> sthAi(dbh1i)
            dbh1o -> dbh2i

    create new sth from dbh1o:
            dbh2o -> dbh1i
            sthAo -> sthAi(dbh1i)
            dbh1o -> dbh2i
            sthBo -> sthBi(dbh2i)

    swap_inner_handle sthAo with sthBo:
            dbh2o -> dbh1i
            sthBo -> sthAi(dbh1i)
            dbh1o -> dbh2i
            sthAo -> sthBi(dbh2i)

visit_child_handles

  $h->visit_child_handles( $coderef );
  $h->visit_child_handles( $coderef, $info );

Where $coderef is a reference to a subroutine and $info is an arbitrary value which, if undefined, defaults to a reference to an empty hash. Returns $info.

$coderef はサブルーチンへのリファレンスで、$info は任意の値であり、 もし未定義ならデフォルトはからハッシュへのリファレンスとなります。 $info を返します。

For each child handle of $h, if any, $coderef is invoked as:

子ハンドルがあれば、各ハンドル $h 毎に、$coderef は以下のようにして 起動されます:

  $coderef->($child_handle, $info);

If the execution of $coderef returns a true value then visit_child_handles is called on that child handle and passed the returned value as $info.

$coderef の実行によって真の値が返されると、"visit_child_handles" が 子ハンドルに呼び出され、返された値を $info として渡します。

For example:

例えば:

  # count database connections with names (DSN) matching a pattern
  my $connections = 0;
  $dbh->{Driver}->visit_child_handles(sub {
      my ($h, $info) = @_;
      ++$connections if $h->{Name} =~ /foo/;
      return 0; # don't visit kids
  })

See also "visit_handles".

"visit_handles" も参照してください。

全てのハンドルに共通の属性

These attributes are common to all types of DBI handles.

これらの属性はDBIの全種類のハンドルについて共通です。

Some attributes are inherited by child handles. That is, the value of an inherited attribute in a newly created statement handle is the same as the value in the parent database handle. Changes to attributes in the new statement handle do not affect the parent database handle and changes to the database handle do not affect existing statement handles, only future ones.

属性によっては、子供に継承されるものもあります。つまり新しく作られる 文ハンドルでの継承される属性の値は、その親となる データベースハンドルでの値と同じになります。 新しい文ハンドルでの属性を変更しても親のデータベースハンドルには 影響を与えませんし、データベースハンドルの属性を変更しても、 既存の文ハンドルには影響を与えません。 新しく作られるものだけです。

Attempting to set or get the value of an unknown attribute generates a warning, except for private driver specific attributes (which all have names starting with a lowercase letter).

ドライバ特有のプライベートな属性(これらの名前は小文字ではじまります)を 除いては、決められていない属性を設定あるいは取得しようとすると致命的な エラーになります。

Example:

例:

  $h->{AttributeName} = ...;    # set/write
  ... = $h->{AttributeName};    # get/read

Warn (boolean, inherited)

The Warn attribute enables useful warnings for certain bad practices. It is enabled by default and should only be disabled in rare circumstances. Since warnings are generated using the Perl warn function, they can be intercepted using the Perl $SIG{__WARN__} hook.

Warn 属性はある種のよくない実践に対する有効な警告を有効にします。 デフォルトでは有効になっています。 これはデフォルトで有効になっていて、特殊な状況でのみ無効にするべきです。 警告は Perl の warn 関数を使って生成されるので、Perl の $SIG{__WARN__} フックを使って、割り込むことが可能です。

The Warn attribute is not related to the PrintWarn attribute.

Warn 属性は PrintWarn 属性とは関係ありません。

Active (boolean, read-only)

The Active attribute is true if the handle object is "active". This is rarely used in applications. The exact meaning of active is somewhat vague at the moment. For a database handle it typically means that the handle is connected to a database ($dbh->disconnect sets Active off). For a statement handle it typically means that the handle is a SELECT that may have more data to fetch. (Fetching all the data or calling $sth->finish sets Active off.)

Active 属性は、ハンドルオブジェクトが生きている("Active")であれば 真になります。 アプリケーションで使われることはまずありません。 "Active"の正確な意味は、その時点によって若干違ってきます。 データベースハンドルにとっては、普通そのハンドルがデータベースに 接続されていることを意味します。 ($dbh->disconnectActive をオフにします)。 文ハンドルにとって典型的なものは、まだ取り出せるデータが 存在するであろう SELECT であることを意味します。 (すべてのデータを取り出してしまうか、 $sth->finish を実行すると Active をオフに設定します)。

Executed (boolean)

The Executed attribute is true if the handle object has been "executed". Currently only the $dbh do() method and the $sth execute(), execute_array(), and execute_for_fetch() methods set the Executed attribute.

The Executed attribute is true if the handle object has been "executed". Currently only the $dbh do() method and the $sth execute(), execute_array(), and execute_for_fetch() methods set the Executed attribute. (TBT)

When it's set on a handle it is also set on the parent handle at the same time. So calling execute() on a $sth also sets the Executed attribute on the parent $dbh.

When it's set on a handle it is also set on the parent handle at the same time. So calling execute() on a $sth also sets the Executed attribute on the parent $dbh. (TBT)

The Executed attribute for a database handle is cleared by the commit() and rollback() methods (even if they fail). The Executed attribute of a statement handle is not cleared by the DBI under any circumstances and so acts as a permanent record of whether the statement handle was ever used.

The Executed attribute for a database handle is cleared by the commit() and rollback() methods (even if they fail). The Executed attribute of a statement handle is not cleared by the DBI under any circumstances and so acts as a permanent record of whether the statement handle was ever used. (TBT)

The Executed attribute was added in DBI 1.41.

Executed 属性は DBI 1.41 で追加されました。

Kids (integer, read-only)

For a driver handle, Kids is the number of currently existing database handles that were created from that driver handle. For a database handle, Kids is the number of currently existing statement handles that were created from that database handle. For a statement handle, the value is zero.

ドライバハンドルの場合、Kids はそのドライバハンドルから作られ、現在 存在しているデータベースハンドルの数になります。 データベースハンドルの場合、Kids はそのデータベースハンドルから作られ、 現在存在している文ハンドルの数になります。 文ハンドルの場合、値は 0 です。

ActiveKids (integer, read-only)

Like Kids, but only counting those that are Active (as above).

Kids と同様ですが、Active なものだけをカウントします(上記参照)。

CachedKids (hash ref)

For a database handle, CachedKids returns a reference to the cache (hash) of statement handles created by the "prepare_cached" method. For a driver handle, returns a reference to the cache (hash) of database handles created by the "connect_cached" method.

データベース・ハンドルの場合、CachedKids"prepare_cached" メソッドにより生成された文ハンドルの キャッシュ(ハッシュ)へのリファレンスを返します。 ドライバハンドルの場合、"connect_cached" メソッドにより作成された 文ハンドルのキャッシュ(ハッシュ)へのリファレンスを返します。

Type (scalar, read-only)

The Type attribute identifies the type of a DBI handle. Returns "dr" for driver handles, "db" for database handles and "st" for statement handles.

The Type attribute identifies the type of a DBI handle. Returns "dr" for driver handles, "db" for database handles and "st" for statement handles. (TBT)

ChildHandles (array ref)

The ChildHandles attribute contains a reference to an array of all the handles created by this handle which are still accessible. The contents of the array are weak-refs and will become undef when the handle goes out of scope.

The ChildHandles attribute contains a reference to an array of all the handles created by this handle which are still accessible. The contents of the array are weak-refs and will become undef when the handle goes out of scope. (TBT)

ChildHandles returns undef if your perl version does not support weak references (check the Scalar::Util module). The referenced array returned should be treated as read-only.

ChildHandles returns undef if your perl version does not support weak references (check the Scalar::Util module). The referenced array returned should be treated as read-only. (TBT)

For example, to enumerate all driver handles, database handles and statement handles:

例えば、全てのドライバハンドル、データベースハンドル、文ハンドルを 数え上げるには:

    sub show_child_handles {
        my ($h, $level) = @_;
        printf "%sh %s %s\n", $h->{Type}, "\t" x $level, $h;
        show_child_handles($_, $level + 1)
            for (grep { defined } @{$h->{ChildHandles}});
    }

    my %drivers = DBI->installed_drivers();
    show_child_handles($_, 0) for (values %drivers);

CompatMode (boolean, inherited)

The CompatMode attribute is used by emulation layers (such as Oraperl) to enable compatible behaviour in the underlying driver (e.g., DBD::Oracle) for this handle. Not normally set by application code.

CompatMode 属性は(Oraperl のような)エミュレーション層レイヤで使われ、 このハンドルのために元になっているドライバ(例えばDBD::Oracle)で 互換性のある動きをすることを可能にします。 アプリケーションプログラムでは通常使われることはありません。

It also has the effect of disabling the 'quick FETCH' of attribute values from the handles attribute cache. So all attribute values are handled by the drivers own FETCH method. This makes them slightly slower but is useful for special-purpose drivers like DBD::Multiplex.

It also has the effect of disabling the 'quick FETCH' of attribute values from the handles attribute cache. So all attribute values are handled by the drivers own FETCH method. This makes them slightly slower but is useful for special-purpose drivers like DBD::Multiplex. (TBT)

InactiveDestroy (boolean)

The default value, false, means a handle will be fully destroyed as normal when the last reference to it is removed, just as you'd expect.

デフォルト値である偽は、予想している通り、ハンドルへの最後のリファレンスが 削除されると通常通り完全に破壊されることを意味します。

If set true then the handle will be treated by the DESTROY as if it was no longer Active, and so the database engine related effects of DESTROYing a handle will be skipped.

If set true then the handle will be treated by the DESTROY as if it was no longer Active, and so the database engine related effects of DESTROYing a handle will be skipped. (TBT)

Think of the name as meaning 'treat the handle as not-Active in the DESTROY method'.

名前は「ハンドルを、DESTROY メソッド内では非アクティブとして扱う」という 意味です。

For a database handle, this attribute does not disable an explicit call to the disconnect method, only the implicit call from DESTROY that happens if the handle is still marked as Active.

データベースハンドルにとっては、この属性は disconnect メソッドの 明示的な 呼び出しを無効にせず、ハンドルに Active とマークされている ときに DESTROY から暗黙の呼び出しだけを無効にします。

This attribute is specifically designed for use in Unix applications that "fork" child processes. Either the parent or the child process, but not both, should set InactiveDestroy true on all their shared handles. (Note that some databases, including Oracle, don't support passing a database connection across a fork.)

この属性は、特に子プロセスを "fork" する UNIX アプリケーションでの 使用について設計されています。 親と子の両方ではなくどちらか片方だけが、共有しているハンドルのすべてに InactiveDestroy を設定するべきです。 (Oracle を含めて、いくつかのドライバはデータベース接続を fork をまたがって 渡すことをサポートしていないことに注意してください。)

To help tracing applications using fork the process id is shown in the trace log whenever a DBI or handle trace() method is called. The process id also shown for every method call if the DBI trace level (not handle trace level) is set high enough to show the trace from the DBI's method dispatcher, e.g. >= 9.

To help tracing applications using fork the process id is shown in the trace log whenever a DBI or handle trace() method is called. The process id also shown for every method call if the DBI trace level (not handle trace level) is set high enough to show the trace from the DBI's method dispatcher, e.g. >= 9. (TBT)

PrintWarn (boolean, inherited)

The PrintWarn attribute controls the printing of warnings recorded by the driver. When set to a true value the DBI will check method calls to see if a warning condition has been set. If so, the DBI will effectively do a warn("$class $method warning: $DBI::errstr") where $class is the driver class and $method is the name of the method which failed. E.g.,

The PrintWarn attribute controls the printing of warnings recorded by the driver. When set to a true value the DBI will check method calls to see if a warning condition has been set. If so, the DBI will effectively do a warn("$class $method warning: $DBI::errstr") where $class is the driver class and $method is the name of the method which failed. E.g., (TBT)

  DBD::Oracle::db execute warning: ... warning text here ...

By default, DBI->connect sets PrintWarn "on" if $^W is true, i.e., perl is running with warnings enabled.

$^W が真なら PrintWarn 属性のデフォルトはオンです; つまり、perl は 警告を有効にして動作します。

If desired, the warnings can be caught and processed using a $SIG{__WARN__} handler or modules like CGI::Carp and CGI::ErrorWrap.

望むなら、警告は $SIG{__WARN__} ハンドラおよび CGI::Carp や CGI::ErrorWrap モジュールで捕捉して処理できます。

See also "set_err" for how warnings are recorded and "HandleSetErr" for how to influence it.

警告がどのように記録されるかについては "set_err" も、それがどのように 影響を与えるかについては "HandleSetErr" も参照してください。

Fetching the full details of warnings can require an extra round-trip to the database server for some drivers. In which case the driver may opt to only fetch the full details of warnings if the PrintWarn attribute is true. If PrintWarn is false then these drivers should still indicate the fact that there were warnings by setting the warning string to, for example: "3 warnings".

Fetching the full details of warnings can require an extra round-trip to the database server for some drivers. In which case the driver may opt to only fetch the full details of warnings if the PrintWarn attribute is true. If PrintWarn is false then these drivers should still indicate the fact that there were warnings by setting the warning string to, for example: "3 warnings". (TBT)

PrintError (boolean, inherited)

The PrintError attribute can be used to force errors to generate warnings (using warn) in addition to returning error codes in the normal way. When set "on", any method which results in an error occurring will cause the DBI to effectively do a warn("$class $method failed: $DBI::errstr") where $class is the driver class and $method is the name of the method which failed. E.g.,

PrintError 属性は、エラーが発生したら、通常の方法でエラーコードを 返すことに加えて、(warn を使って)警告を生成するように強制します。 "on"に設定されているとき、なんらかのメソッドがエラーになると、DBI に 事実上 warn("$class $method failed: $DBI::errstr") を実行させます; $class にはドライバクラス、$method には失敗したメソッドが入ります。 例えば

  DBD::Oracle::db prepare failed: ... error text here ...

By default, DBI->connect sets PrintError "on".

デフォルトでは、DBI->connectPrintError を "on" に設定します。

If desired, the warnings can be caught and processed using a $SIG{__WARN__} handler or modules like CGI::Carp and CGI::ErrorWrap.

もし望むなら、$SIG{__WARN__} ハンドラや CGI::Carp, CGI::ErrorWrap のような モジュールを使って、警告を捕らえ処理することができます。

RaiseError (boolean, inherited)

The RaiseError attribute can be used to force errors to raise exceptions rather than simply return error codes in the normal way. It is "off" by default. When set "on", any method which results in an error will cause the DBI to effectively do a die("$class $method failed: $DBI::errstr"), where $class is the driver class and $method is the name of the method that failed. E.g.,

RaiseError 属性はエラー発生時に通常通り単にエラーコードを返すのではなく、 例外を発生させるために使われます。 デフォルトは"off"です。 "on" に設定されているとき、なんらかのメソッドでエラーになると、DBI に 事実上 die("$class $method failed: $DBI::errstr") を実行させます; $class にはドライバクラス、$method には失敗したメソッドが入ります。 例えば

  DBD::Oracle::db prepare failed: ... error text here ...

If you turn RaiseError on then you'd normally turn PrintError off. If PrintError is also on, then the PrintError is done first (naturally).

RaiseError をオンにすると、普通 PrintError はオフにします。 PrintError もオンにすると、(自然なように) PrintError がまず 実行されます。

Typically RaiseError is used in conjunction with eval { ... } to catch the exception that's been thrown and followed by an if ($@) { ... } block to handle the caught exception. For example:

Typically RaiseError is used in conjunction with eval { ... } to catch the exception that's been thrown and followed by an if ($@) { ... } block to handle the caught exception. For example: (TBT)

  eval {
    ...
    $sth->execute();
    ...
  };
  if ($@) {
    # $sth->err and $DBI::err will be true if error was from DBI
    warn $@; # print the error
    ... # do whatever you need to deal with the error
  }

In that eval block the $DBI::lasth variable can be useful for diagnosis and reporting if you can't be sure which handle triggered the error. For example, $DBI::lasth->{Type} and $DBI::lasth->{Statement}.

In that eval block the $DBI::lasth variable can be useful for diagnosis and reporting if you can't be sure which handle triggered the error. For example, $DBI::lasth->{Type} and $DBI::lasth->{Statement}. (TBT)

See also "Transactions".

"Transactions" も参照してください。

If you want to temporarily turn RaiseError off (inside a library function that is likely to fail, for example), the recommended way is like this:

一時的に RaiseError をオフに切り替えたいのであれば(例えば障害が 発生しやすいライブラリ関数の内部など)、以下のようにすることをお勧めします:

  {
    local $h->{RaiseError};  # localize and turn off for this block
    ...
  }

The original value will automatically and reliably be restored by Perl, regardless of how the block is exited. The same logic applies to other attributes, including PrintError.

そのブロックからどのように抜けたのかは関係なく、元の値は自動的に、信頼性を 持って Perl により保存されます。 PrintError も含めて、他の属性についても同じロジックが適用されます。

HandleError (code ref, inherited)

The HandleError attribute can be used to provide your own alternative behaviour in case of errors. If set to a reference to a subroutine then that subroutine is called when an error is detected (at the same point that RaiseError and PrintError are handled).

The HandleError attribute can be used to provide your own alternative behaviour in case of errors. If set to a reference to a subroutine then that subroutine is called when an error is detected (at the same point that RaiseError and PrintError are handled). (TBT)

The subroutine is called with three parameters: the error message string that RaiseError and PrintError would use, the DBI handle being used, and the first value being returned by the method that failed (typically undef).

The subroutine is called with three parameters: the error message string that RaiseError and PrintError would use, the DBI handle being used, and the first value being returned by the method that failed (typically undef). (TBT)

If the subroutine returns a false value then the RaiseError and/or PrintError attributes are checked and acted upon as normal.

サブルーチンが偽の値を返すと、RaiseError 属性や PrintError 属性が チェックされ、通常通り動作します。

For example, to die with a full stack trace for any error:

例えば、全てのエラーについて完全なスタックトレースと共に die させるには:

  use Carp;
  $h->{HandleError} = sub { confess(shift) };

Or to turn errors into exceptions:

またはエラーを例外に変換するには:

  use Exception; # or your own favourite exception module
  $h->{HandleError} = sub { Exception->new('DBI')->raise($_[0]) };

It is possible to 'stack' multiple HandleError handlers by using closures:

クロージャを使うことで複数の HandleError ハンドラを「スタック」させることが できます:

  sub your_subroutine {
    my $previous_handler = $h->{HandleError};
    $h->{HandleError} = sub {
      return 1 if $previous_handler and &$previous_handler(@_);
      ... your code here ...
    };
  }

Using a my inside a subroutine to store the previous HandleError value is important. See perlsub and perlref for more information about closures.

Using a my inside a subroutine to store the previous HandleError value is important. See perlsub and perlref for more information about closures. (TBT)

It is possible for HandleError to alter the error message that will be used by RaiseError and PrintError if it returns false. It can do that by altering the value of $_[0]. This example appends a stack trace to all errors and, unlike the previous example using Carp::confess, this will work PrintError as well as RaiseError:

It is possible for HandleError to alter the error message that will be used by RaiseError and PrintError if it returns false. It can do that by altering the value of $_[0]. This example appends a stack trace to all errors and, unlike the previous example using Carp::confess, this will work PrintError as well as RaiseError: (TBT)

  $h->{HandleError} = sub { $_[0]=Carp::longmess($_[0]); 0; };

It is also possible for HandleError to hide an error, to a limited degree, by using "set_err" to reset $DBI::err and $DBI::errstr, and altering the return value of the failed method. For example:

It is also possible for HandleError to hide an error, to a limited degree, by using "set_err" to reset $DBI::err and $DBI::errstr, and altering the return value of the failed method. For example: (TBT)

  $h->{HandleError} = sub {
    return 0 unless $_[0] =~ /^\S+ fetchrow_arrayref failed:/;
    return 0 unless $_[1]->err == 1234; # the error to 'hide'
    $h->set_err(undef,undef);   # turn off the error
    $_[2] = [ ... ];    # supply alternative return value
    return 1;
  };

This only works for methods which return a single value and is hard to make reliable (avoiding infinite loops, for example) and so isn't recommended for general use! If you find a good use for it then please let me know.

This only works for methods which return a single value and is hard to make reliable (avoiding infinite loops, for example) and so isn't recommended for general use! If you find a good use for it then please let me know. (TBT)

HandleSetErr (code ref, inherited)

The HandleSetErr attribute can be used to intercept the setting of handle err, errstr, and state values. If set to a reference to a subroutine then that subroutine is called whenever set_err() is called, typically by the driver or a subclass.

The HandleSetErr attribute can be used to intercept the setting of handle err, errstr, and state values. If set to a reference to a subroutine then that subroutine is called whenever set_err() is called, typically by the driver or a subclass. (TBT)

The subroutine is called with five arguments, the first five that were passed to set_err(): the handle, the err, errstr, and state values being set, and the method name. These can be altered by changing the values in the @_ array. The return value affects set_err() behaviour, see "set_err" for details.

The subroutine is called with five arguments, the first five that were passed to set_err(): the handle, the err, errstr, and state values being set, and the method name. These can be altered by changing the values in the @_ array. The return value affects set_err() behaviour, see "set_err" for details. (TBT)

It is possible to 'stack' multiple HandleSetErr handlers by using closures. See "HandleError" for an example.

クロージャを使うことで複数の HandleSetErr ハンドラを 「スタック」させることができます: 例については "HandleError" を参照してください。

The HandleSetErr and HandleError subroutines differ in subtle but significant ways. HandleError is only invoked at the point where the DBI is about to return to the application with err set true. It's not invoked by the failure of a method that's been called by another DBI method. HandleSetErr, on the other hand, is called whenever set_err() is called with a defined err value, even if false. So it's not just for errors, despite the name, but also warn and info states. The set_err() method, and thus HandleSetErr, may be called multiple times within a method and is usually invoked from deep within driver code.

The HandleSetErr and HandleError subroutines differ in subtle but significant ways. HandleError is only invoked at the point where the DBI is about to return to the application with err set true. It's not invoked by the failure of a method that's been called by another DBI method. HandleSetErr, on the other hand, is called whenever set_err() is called with a defined err value, even if false. So it's not just for errors, despite the name, but also warn and info states. The set_err() method, and thus HandleSetErr, may be called multiple times within a method and is usually invoked from deep within driver code. (TBT)

In theory a driver can use the return value from HandleSetErr via set_err() to decide whether to continue or not. If set_err() returns an empty list, indicating that the HandleSetErr code has 'handled' the 'error', the driver could then continue instead of failing (if that's a reasonable thing to do). This isn't excepted to be common and any such cases should be clearly marked in the driver documentation and discussed on the dbi-dev mailing list.

In theory a driver can use the return value from HandleSetErr via set_err() to decide whether to continue or not. If set_err() returns an empty list, indicating that the HandleSetErr code has 'handled' the 'error', the driver could then continue instead of failing (if that's a reasonable thing to do). This isn't excepted to be common and any such cases should be clearly marked in the driver documentation and discussed on the dbi-dev mailing list. (TBT)

The HandleSetErr attribute was added in DBI 1.41.

HandleSetErr 属性は DBI 1.41 で追加されました。

ErrCount (unsigned integer)

The ErrCount attribute is incremented whenever the set_err() method records an error. It isn't incremented by warnings or information states. It is not reset by the DBI at any time.

The ErrCount attribute is incremented whenever the set_err() method records an error. It isn't incremented by warnings or information states. It is not reset by the DBI at any time. (TBT)

The ErrCount attribute was added in DBI 1.41. Older drivers may not have been updated to use set_err() to record errors and so this attribute may not be incremented when using them.

The ErrCount attribute was added in DBI 1.41. Older drivers may not have been updated to use set_err() to record errors and so this attribute may not be incremented when using them. (TBT)

ShowErrorStatement (boolean, inherited)

The ShowErrorStatement attribute can be used to cause the relevant Statement text to be appended to the error messages generated by the RaiseError, PrintError, and PrintWarn attributes. Only applies to errors on statement handles plus the prepare(), do(), and the various select*() database handle methods. (The exact format of the appended text is subject to change.)

The ShowErrorStatement attribute can be used to cause the relevant Statement text to be appended to the error messages generated by the RaiseError, PrintError, and PrintWarn attributes. Only applies to errors on statement handles plus the prepare(), do(), and the various select*() database handle methods. (The exact format of the appended text is subject to change.) (TBT)

If $h->{ParamValues} returns a hash reference of parameter (placeholder) values then those are formatted and appended to the end of the Statement text in the error message.

If $h->{ParamValues} returns a hash reference of parameter (placeholder) values then those are formatted and appended to the end of the Statement text in the error message. (TBT)

TraceLevel (integer, inherited)

The TraceLevel attribute can be used as an alternative to the "trace" method to set the DBI trace level and trace flags for a specific handle. See "TRACING" for more details.

The TraceLevel attribute can be used as an alternative to the "trace" method to set the DBI trace level and trace flags for a specific handle. See "TRACING" for more details. (TBT)

The TraceLevel attribute is especially useful combined with local to alter the trace settings for just a single block of code.

TraceLevel 属性は、特定の一つのブロックのコードでだけトレース設定を 変更するために local を組み合わせると特に便利です。

FetchHashKeyName (string, inherited)

The FetchHashKeyName attribute is used to specify whether the fetchrow_hashref() method should perform case conversion on the field names used for the hash keys. For historical reasons it defaults to 'NAME' but it is recommended to set it to 'NAME_lc' (convert to lower case) or 'NAME_uc' (convert to upper case) according to your preference. It can only be set for driver and database handles. For statement handles the value is frozen when prepare() is called.

The FetchHashKeyName attribute is used to specify whether the fetchrow_hashref() method should perform case conversion on the field names used for the hash keys. For historical reasons it defaults to 'NAME' but it is recommended to set it to 'NAME_lc' (convert to lower case) or 'NAME_uc' (convert to upper case) according to your preference. It can only be set for driver and database handles. For statement handles the value is frozen when prepare() is called. (TBT)

ChopBlanks (boolean, inherited)

The ChopBlanks attribute can be used to control the trimming of trailing space characters from fixed width character (CHAR) fields. No other field types are affected, even where field values have trailing spaces.

ChopBlanks 属性は固定長文字列(CHAR)フィールドから末尾の空白を 取り除くことを制御するために使われます。 他のフィールドタイプには、例え末尾に空白がついていても、影響与えません。

The default is false (although it is possible that the default may change). Applications that need specific behaviour should set the attribute as needed.

デフォルトは偽です。 (しかしデフォルトが変更される可能性があります)。 特定の動きが必要なアプリケーションは、この属性を必要な値に設定します。

Drivers are not required to support this attribute, but any driver which does not support it must arrange to return undef as the attribute value.

ドライバはこの属性をサポートしなければならないわけではありません。 しかしサポートしていないドライバはこの属性の値として undef を 返すようにしなければなりません。

LongReadLen (unsigned integer, inherited)

The LongReadLen attribute may be used to control the maximum length of 'long' type fields (LONG, BLOB, CLOB, MEMO, etc.) which the driver will read from the database automatically when it fetches each row of data.

LongReadLen 属性は、データ行を取り出す際に、ドライバがデータベースから 自動的に読みこむ「長い」フィールド(LONG, BLOB, CLOB, MEMO など)の 最大長を制御するために使われます。

The LongReadLen attribute only relates to fetching and reading long values; it is not involved in inserting or updating them.

LongReadLen 属性は「長い」値の取り出しと読みこみにだけ関連します; 挿入や更新のときには関係しません。

A value of 0 means not to automatically fetch any long data. Drivers may return undef or an empty string for long fields when LongReadLen is 0.

値が 0 は、「長い」データは自動的に取り出されないことを意味します。 LongReadLen が 0 のとき、「長い」フィールドの値は undef または 空文字列になります。

The default is typically 0 (zero) or 80 bytes but may vary between drivers. Applications fetching long fields should set this value to slightly larger than the longest long field value to be fetched.

デフォルトは通常 0 または 80 バイトですが、ドライバによって違うかもしれません。 「長い」フィールドを取り出すアプリケーションは、取り出される 「長い」フィールドの最大長よりもちょっとだけ大きい値を、 この値に設定しなければなりません。

Some databases return some long types encoded as pairs of hex digits. For these types, LongReadLen relates to the underlying data length and not the doubled-up length of the encoded string.

ある種のデータベースは「長い」タイプを 16 進のペアでエンコードして返す 場合があります。 これらのタイプについては、LongReadLen はエンコードされた文字列の 2 倍になった長さではなく、基になっているデータ長に関係します。

Changing the value of LongReadLen for a statement handle after it has been prepare'd will typically have no effect, so it's common to set LongReadLen on the $dbh before calling prepare.

既に prepare された後に、文ハンドルの LongReadLen を 変更しても、通常、何も影響を与えません; そのため普通、prepare を呼び出す前に、$dbh に対して LongReadLen を 設定します。

For most drivers the value used here has a direct effect on the memory used by the statement handle while it's active, so don't be too generous. If you can't be sure what value to use you could execute an extra select statement to determine the longest value. For example:

ほとんどのドライバではここに使われる値が有効な文ハンドルによって 使われるメモリに対して直接的な影響を与えることに注意してください。 そのため、あまり気前よくならないようにしてください。 この値の使い方がはっきりとわからないなら、一番長い値を決定するために 追加の select 文を実行できます。 例えば:

  $dbh->{LongReadLen} = $dbh->selectrow_array(qq{
      SELECT MAX(OCTET_LENGTH(long_column_name))
      FROM table WHERE ...
  });
  $sth = $dbh->prepare(qq{
      SELECT long_column_name, ... FROM table WHERE ...
  });

You may need to take extra care if the table can be modified between the first select and the second being executed. You may also need to use a different function if OCTET_LENGTH() does not work for long types in your database. For example, for Sybase use DATALENGTH() and for Oracle use LENGTHB().

You may need to take extra care if the table can be modified between the first select and the second being executed. You may also need to use a different function if OCTET_LENGTH() does not work for long types in your database. For example, for Sybase use DATALENGTH() and for Oracle use LENGTHB(). (TBT)

See also "LongTruncOk" for information on truncation of long types.

長い型の切り詰めに関する情報については "LongTruncOk" も参照してください。

LongTruncOk (boolean, inherited)

The LongTruncOk attribute may be used to control the effect of fetching a long field value which has been truncated (typically because it's longer than the value of the LongReadLen attribute).

LongTruncOk 属性は、(通常は LongReadLen 属性よりも長いために) 切り捨てられる「長い」フィールドの取り出しの影響を制御するために使われます。

By default, LongTruncOk is false and so fetching a long value that needs to be truncated will cause the fetch to fail. (Applications should always be sure to check for errors after a fetch loop in case an error, such as a divide by zero or long field truncation, caused the fetch to terminate prematurely.)

デフォルトでは LongTruncOk は偽です; そのため切り捨てられる必要がある 「長い」値を取り出すと取り出し失敗となります。 (アプリケーションは、エラーの場合、取り出しループの後で、エラーを常に確実に チェックしなければなりません。 0 除算、「長い」フィールドの切り捨てなどによって取り出しが早く 終わってしまうことがあります。)

If a fetch fails due to a long field truncation when LongTruncOk is false, many drivers will allow you to continue fetching further rows.

LongTruncOk が偽のとき、「長い」フィールドにより取り出しが失敗しても、 多くのドライバでは先の行を取り出すことができます。

See also "LongReadLen".

"LongReadLen" も参照してください。

TaintIn (boolean, inherited)

If the TaintIn attribute is set to a true value and Perl is running in taint mode (e.g., started with the -T option), then all the arguments to most DBI method calls are checked for being tainted. This may change.

If the TaintIn attribute is set to a true value and Perl is running in taint mode (e.g., started with the -T option), then all the arguments to most DBI method calls are checked for being tainted. This may change. (TBT)

The attribute defaults to off, even if Perl is in taint mode. See perlsec for more about taint mode. If Perl is not running in taint mode, this attribute has no effect.

The attribute defaults to off, even if Perl is in taint mode. See perlsec for more about taint mode. If Perl is not running in taint mode, this attribute has no effect. (TBT)

When fetching data that you trust you can turn off the TaintIn attribute, for that statement handle, for the duration of the fetch loop.

信頼できるデータをフェッチするときには、そのフェッチループの間、 その文ハンドルに対して、TaintIn 属性をオフにできます。

The TaintIn attribute was added in DBI 1.31.

TaintIn 属性は DBI 1.31 で追加されました。

TaintOut (boolean, inherited)

If the TaintOut attribute is set to a true value and Perl is running in taint mode (e.g., started with the -T option), then most data fetched from the database is considered tainted. This may change.

TaintOut 属性に真の値が設定され、かつ Perl が汚染(taint)モード (例えば -T オプションで開始されて)で実行されていれば、データベースから 取り出されるすべてのデータは汚染されているとチェックされます。 これは変更されるかもしれません。

The attribute defaults to off, even if Perl is in taint mode. See perlsec for more about taint mode. If Perl is not running in taint mode, this attribute has no effect.

Perl が汚染モードであっても、この属性のデフォルトはオフです。 汚染モードについてのさらなる情報は perlsec をご覧下さい。 Perl が汚染モードで実行されていなければ、これは何も効果がありません。

When fetching data that you trust you can turn off the TaintOut attribute, for that statement handle, for the duration of the fetch loop.

信頼できるデータを取り出すとき、文ハンドルについて、取り出し ループの間は TaintOut 属性をオフに切り替えることが出来ます。

Currently only fetched data is tainted. It is possible that the results of other DBI method calls, and the value of fetched attributes, may also be tainted in future versions. That change may well break your applications unless you take great care now. If you use DBI Taint mode, please report your experience and any suggestions for changes.

現在は取り出されたデータだけが汚染されているとしています。 将来のバージョンでは他の DBI メソッド呼び出しの結果そして取り出された属性の 値も同様に汚染されているとするかもしれません。 今のうちに細心の注意を払わない限り、その変更はアプリケーションを 壊しかねません。 もし DBI を Taint モードで使うのであれば、変更のためにあなたの経験と提案を 報告してください。

The TaintOut attribute was added in DBI 1.31.

TaintOut 属性は DBI 1.31 で追加されました。

Taint (boolean, inherited)

The Taint attribute is a shortcut for "TaintIn" and "TaintOut" (it is also present for backwards compatibility).

Taint 属性は "TaintIn""TaintOut" へのショートカットです (これはまた後方互換性のためにも存在しています)。

Setting this attribute sets both "TaintIn" and "TaintOut", and retrieving it returns a true value if and only if "TaintIn" and "TaintOut" are both set to true values.

Setting this attribute sets both "TaintIn" and "TaintOut", and retrieving it returns a true value if and only if "TaintIn" and "TaintOut" are both set to true values. (TBT)

Profile (inherited)

The Profile attribute enables the collection and reporting of method call timing statistics. See the DBI::Profile module documentation for much more detail.

Profile 属性は、メソッド呼び出しタイミング統計の収集と報告を 有効にします。 非常に 細かな詳細については DBI::Profile モジュールの文書を 参照してください。

The Profile attribute was added in DBI 1.24.

Profile 属性は DBI 1.24 で追加されました。

ReadOnly (boolean, inherited)

An application can set the ReadOnly attribute of a handle to a true value to indicate that it will not be attempting to make any changes using that handle or any children of it.

An application can set the ReadOnly attribute of a handle to a true value to indicate that it will not be attempting to make any changes using that handle or any children of it. (TBT)

Note that the exact definition of 'read only' is rather fuzzy. For more details see the documentation for the driver you're using.

「読み込み専用」の正確な定義はややあいまいであることに注意してください。 さらなる詳細については使っているドライバの文書を参照してください。

If the driver can make the handle truly read-only then it should (unless doing so would have unpleasant side effect, like changing the consistency level from per-statement to per-session). Otherwise the attribute is simply advisory.

If the driver can make the handle truly read-only then it should (unless doing so would have unpleasant side effect, like changing the consistency level from per-statement to per-session). Otherwise the attribute is simply advisory. (TBT)

A driver can set the ReadOnly attribute itself to indicate that the data it is connected to cannot be changed for some reason.

ドライバは、何らかの理由で変更できないものに接続しているデータであることを 示すために自らの ReadOnly 属性を設定できます。

Library modules and proxy drivers can use the attribute to influence their behavior. For example, the DBD::Gofer driver considers the ReadOnly attribute when making a decision about whether to retry an operation that failed.

Library modules and proxy drivers can use the attribute to influence their behavior. For example, the DBD::Gofer driver considers the ReadOnly attribute when making a decision about whether to retry an operation that failed. (TBT)

The attribute should be set to 1 or 0 (or undef). Other values are reserved.

属性は 1 または 0 (または undef)に設定されるべきです。 その他の値は予約されています。

Callbacks (hash ref)

The DBI callback mechanism lets you intercept, and optionally replace, any method call on a DBI handle. At the extreme, it lets you become a puppet master, deceiving the application in any way you want.

The DBI callback mechanism lets you intercept, and optionally replace, any method call on a DBI handle. At the extreme, it lets you become a puppet master, deceiving the application in any way you want. (TBT)

The Callbacks attribute is a hash reference where the keys are DBI method names and the values are code references. For each key naming a method, the DBI will execute the associated code reference before executing the method.

The Callbacks attribute is a hash reference where the keys are DBI method names and the values are code references. For each key naming a method, the DBI will execute the associated code reference before executing the method. (TBT)

The arguments to the code reference will be the same as to the method, including the invocant (a database handle or statement handle). For example, say that to callback to some code on a call to prepare():

The arguments to the code reference will be the same as to the method, including the invocant (a database handle or statement handle). For example, say that to callback to some code on a call to prepare(): (TBT)

  $dbh->{Callbacks} = {
      prepare => sub {
          my ($dbh, $query, $attrs) = @_;
          print "Preparing q{$query}\n"
      },
  };

The callback would then be executed when you called the prepare() method:

prepare() メソッドを呼び出したときに、コールバックが実行されます:

  $dbh->prepare('SELECT 1');

And the output of course would be:

そして出力はもちろん以下のようになります:

  Preparing q{SELECT 1}

Because callbacks are executed before the methods they're associated with, you can modify the arguments before they're passed on to the method call. For example, to make sure that all calls to prepare() are immediately prepared by DBD::Pg, add a callback that makes sure that the pg_prepare_now attribute is always set:

Because callbacks are executed before the methods they're associated with, you can modify the arguments before they're passed on to the method call. For example, to make sure that all calls to prepare() are immediately prepared by DBD::Pg, add a callback that makes sure that the pg_prepare_now attribute is always set: (TBT)

  my $dbh = DBI->connect($dsn, $username, $auth, {
      Callbacks => {
          prepare => sub {
              $_[2] ||= {};
              $_[2]->{pg_prepare_now} = 1;
              return; # must return nothing
          },
      }
  });

Note that we are editing the contents of @_ directly. In this case we've created the attributes hash if it's not passed to the prepare call.

@_ の内容を直接編集していることに注意してください。 この場合、これが prepare 呼び出しに渡されないなら属性ハッシュを 作成しています。

You can also prevent the associated method from ever executing. While a callback executes, $_ holds the method name. (This allows multiple callbacks to share the same code reference and still know what method was called.) To prevent the method from executing, simply undef $_. For example, if you wanted to disable calls to ping(), you could do this:

You can also prevent the associated method from ever executing. While a callback executes, $_ holds the method name. (This allows multiple callbacks to share the same code reference and still know what method was called.) To prevent the method from executing, simply undef $_. For example, if you wanted to disable calls to ping(), you could do this: (TBT)

  $dbh->{Callbacks} = {
      ping => sub {
          # tell dispatch to not call the method:
          undef $_;
          # return this value instead:
          return "42 bells";
      }
  };

As with other attributes, Callbacks can be specified on a handle or via the attributes to connect(). Callbacks can also be applied to a statement methods on a statement handle. For example:

As with other attributes, Callbacks can be specified on a handle or via the attributes to connect(). Callbacks can also be applied to a statement methods on a statement handle. For example: (TBT)

  $sth->{Callbacks} = {
      execute => sub {
          print "Executing ", shift->{Statement}, "\n";
      }
  };

The Callbacks attribute of a database handle isn't copied to any statement handles it creates. So setting callbacks for a statement handle requires you to set the Callbacks attribute on the statement handle yourself, as in the example above, or use the special ChildCallbacks key described below.

The Callbacks attribute of a database handle isn't copied to any statement handles it creates. So setting callbacks for a statement handle requires you to set the Callbacks attribute on the statement handle yourself, as in the example above, or use the special ChildCallbacks key described below. (TBT)

Special Keys in Callbacks Attribute

Callbacks 属性の特殊キー

In addition to DBI handle method names, the Callbacks hash reference supports three additional keys.

DBI ハンドルメソッド名に加えて、Callbacks ハッシュリファレンスは 三つの追加のキーに対応しています。

The first is the ChildCallbacks key. When a statement handle is created from a database handle the ChildCallbacks key of the database handle's Callbacks attribute, if any, becomes the new Callbacks attribute of the statement handle. This allows you to define callbacks for all statement handles created from a database handle. For example, if you wanted to count how many times execute was called in your application, you could write:

The first is the ChildCallbacks key. When a statement handle is created from a database handle the ChildCallbacks key of the database handle's Callbacks attribute, if any, becomes the new Callbacks attribute of the statement handle. This allows you to define callbacks for all statement handles created from a database handle. For example, if you wanted to count how many times execute was called in your application, you could write: (TBT)

  my $exec_count = 0;
  my $dbh = DBI->connect( $dsn, $username, $auth, {
      Callbacks => {
          ChildCallbacks => {
              execute => sub { $exec_count++; return; }
          }
      }
  });

  END {
      print "The execute method was called $exec_count times\n";
  }

The other two special keys are connect_cached.new and connect_cached.reused. These keys define callbacks that are called when connect_cached() is called, but allow different behaviors depending on whether a new handle is created or a handle is returned. The callback is invoked with these arguments: $dbh, $dsn, $user, $auth, $attr.

The other two special keys are connect_cached.new and connect_cached.reused. These keys define callbacks that are called when connect_cached() is called, but allow different behaviors depending on whether a new handle is created or a handle is returned. The callback is invoked with these arguments: $dbh, $dsn, $user, $auth, $attr. (TBT)

For example, some applications uses connect_cached() to connect with AutoCommit enabled and then disable AutoCommit temporarily for transactions. If connect_cached() is called during a transaction, perhaps in a utility method, then it might select the same cached handle and then force AutoCommit on, forcing a commit of the transaction. See the "connect_cached" documentation for one way to deal with that. Here we'll describe an alternative approach using a callback.

For example, some applications uses connect_cached() to connect with AutoCommit enabled and then disable AutoCommit temporarily for transactions. If connect_cached() is called during a transaction, perhaps in a utility method, then it might select the same cached handle and then force AutoCommit on, forcing a commit of the transaction. See the "connect_cached" documentation for one way to deal with that. Here we'll describe an alternative approach using a callback. (TBT)

Because the connect_cached.* callbacks are invoked before connect_cached() has applied the connect attributes you can use a callback to edit the attributes that will be applied. To prevent a cached handle from having its transactions committed before it's returned, you can eliminate the AutoCommit attribute in a connect_cached.reused callback, like so:

Because the connect_cached.* callbacks are invoked before connect_cached() has applied the connect attributes you can use a callback to edit the attributes that will be applied. To prevent a cached handle from having its transactions committed before it's returned, you can eliminate the AutoCommit attribute in a connect_cached.reused callback, like so: (TBT)

  my $cb = {
      窶歪onnect_cached.reused窶?=> sub { delete $_[4]->{AutoCommit} },
  };

  sub dbh {
      my $self = shift;
      DBI->connect_cached( $dsn, $username, $auth, {
          PrintError => 0,
          RaiseError => 1,
          AutoCommit => 1,
          Callbacks  => $cb,
      });
  }

The upshot is that new database handles are created with AutoCommit enabled, while cached database handles are left in whatever transaction state they happened to be in when retrieved from the cache.

The upshot is that new database handles are created with AutoCommit enabled, while cached database handles are left in whatever transaction state they happened to be in when retrieved from the cache. (TBT)

A more common application for callbacks is setting connection state only when a new connection is made (by connect() or connect_cached()). Adding a callback to the connected method makes this easy. This method is a no-op by default (unless you subclass the DBI and change it). The DBI calls it to indicate that a new connection has been made and the connection attributes have all been set. You can give it a bit of added functionality by applying a callback to it. For example, to make sure that MySQL understands your application's ANSI-compliant SQL, set it up like so:

A more common application for callbacks is setting connection state only when a new connection is made (by connect() or connect_cached()). Adding a callback to the connected method makes this easy. This method is a no-op by default (unless you subclass the DBI and change it). The DBI calls it to indicate that a new connection has been made and the connection attributes have all been set. You can give it a bit of added functionality by applying a callback to it. For example, to make sure that MySQL understands your application's ANSI-compliant SQL, set it up like so: (TBT)

  my $dbh = DBI->connect($dsn, $username, $auth, {
      Callbacks => {
          connected => sub {
              shift->do(q{
                  SET SESSION sql_mode='ansi,strict_trans_tables,no_auto_value_on_zero';
              });
              return;
          },
      }
  });

One significant limitation with callbacks is that there can only be one per method per handle. This means it's easy for one use of callbacks to interfere with, or typically simply overwrite, another use of callbacks. For this reason modules using callbacks should document the fact clearly so application authors can tell if use of callbacks by the module will clash with use of callbacks by the application.

One significant limitation with callbacks is that there can only be one per method per handle. This means it's easy for one use of callbacks to interfere with, or typically simply overwrite, another use of callbacks. For this reason modules using callbacks should document the fact clearly so application authors can tell if use of callbacks by the module will clash with use of callbacks by the application. (TBT)

You might be able to work around this issue by taking a copy of the original callback and calling it within your own. For example:

元のコールバックのコピーを取って、そちらを呼ぶことでこの問題を 回避できるかもしれません。 例えば:

  my $prev_cb = $h->{Callbacks}{method_name};
  $h->{Callbacks}{method_name} = sub {
    if ($prev_cb) {
        my @result = $prev_cb->(@_);
        return @result if not $_; # $prev_cb vetoed call
    }
    ... your callback logic here ...
  };

private_your_module_name_*

The DBI provides a way to store extra information in a DBI handle as "private" attributes. The DBI will allow you to store and retrieve any attribute which has a name starting with "private_".

DBI は「プライベート」属性として、DBI ハンドルでの特別な情報を格納する 方法を提供しています。 DBI では "private_" で始まる名前の属性を格納、参照することができます。

It is strongly recommended that you use just one private attribute (e.g., use a hash ref) and give it a long and unambiguous name that includes the module or application name that the attribute relates to (e.g., "private_YourFullModuleName_thingy").

ただしプライベート属性は(例えばハッシュのリファレンスを使うなどにより) 一つ だけとし、かつ その属性に関連するモジュールまたは アプリケーション名が入った長くて他にはないような名前にすることを 強く お勧めします(例えば "private_YourFullModuleName_thingy")。

Because of the way the Perl tie mechanism works you cannot reliably use the ||= operator directly to initialise the attribute, like this:

Perl の tie 機構の動作手法により、以下のように、属性を初期化するために 信頼できる形で||= 演算子を直接使うことはできません。

  my $foo = $dbh->{private_yourmodname_foo} ||= { ... }; # WRONG

you should use a two step approach like this:

以下のように二段階の手法を使うべきです:

  my $foo = $dbh->{private_yourmodname_foo};
  $foo ||= $dbh->{private_yourmodname_foo} = { ... };

This attribute is primarily of interest to people sub-classing DBI, or for applications to piggy-back extra information onto DBI handles.

この属性は基本的に DBI をサブクラス化する人々や、DBI ハンドルに その他の情報を追加するアプリケーションが関心を持つものです。

DBI データベースハンドルオブジェクト

This section covers the methods and attributes associated with database handles.

このセクションはデータベース・ハンドルに関連するメソッドと属性について カバーします。

データベースハンドルメソッド

The following methods are specified for DBI database handles:

以下のメソッドがDBIデータベース・ハンドルに指定されています:

clone

  $new_dbh = $dbh->clone();
  $new_dbh = $dbh->clone(\%attr);

The clone method duplicates the $dbh connection by connecting with the same parameters ($dsn, $user, $password) as originally used.

clone メソッドは、$dbh 接続を、同じパラメータ ($dsn, $user, $password) で 接続することで複製します。

The attributes for the cloned connect are the same as those used for the original connect, with some other attributes merged over them depending on the \%attr parameter.

複製された接続の属性は元の接続のものと同じものに、\%attr 引数によるものが マージされたものです。

If \%attr is given then the attributes it contains are merged into the original attributes and override any with the same names. Effectively the same as doing:

If \%attr is given then the attributes it contains are merged into the original attributes and override any with the same names. Effectively the same as doing: (TBT)

  %attribues_used = ( %original_attributes, %attr );

If \%attr is not given then it defaults to a hash containing all the attributes in the attribute cache of $dbh excluding any non-code references, plus the main boolean attributes (RaiseError, PrintError, AutoCommit, etc.). This behaviour is subject to change.

If \%attr is not given then it defaults to a hash containing all the attributes in the attribute cache of $dbh excluding any non-code references, plus the main boolean attributes (RaiseError, PrintError, AutoCommit, etc.). This behaviour is subject to change. (TBT)

The clone method can be used even if the database handle is disconnected.

clone メソッドは例えばデータベースハンドルの接続が切れていても使えます。

The clone method was added in DBI 1.33. It is very new and likely to change.

clone メソッドは DBI 1.33 で追加されました。 これはとても新しく、変更されるかもしれません。

data_sources

  @ary = $dbh->data_sources();
  @ary = $dbh->data_sources(\%attr);

Returns a list of data sources (databases) available via the $dbh driver's data_sources() method, plus any extra data sources that the driver can discover via the connected $dbh. Typically the extra data sources are other databases managed by the same server process that the $dbh is connected to.

Returns a list of data sources (databases) available via the $dbh driver's data_sources() method, plus any extra data sources that the driver can discover via the connected $dbh. Typically the extra data sources are other databases managed by the same server process that the $dbh is connected to. (TBT)

Data sources are returned in a form suitable for passing to the "connect" method (that is, they will include the "dbi:$driver:" prefix).

データソースは "connect" メソッドに渡すのに適した形 (つまり、"dbi:$driver:" 前置詞を含む形) で返されます。

The data_sources() method, for a $dbh, was added in DBI 1.38.

$dbh のための data_sources() メソッドは DBI 1.38 で追加されました。

do

  $rows = $dbh->do($statement)           or die $dbh->errstr;
  $rows = $dbh->do($statement, \%attr)   or die $dbh->errstr;
  $rows = $dbh->do($statement, \%attr, @bind_values) or die ...

Prepare and execute a single statement. Returns the number of rows affected or undef on error. A return value of -1 means the number of rows is not known, not applicable, or not available.

一つの文を prepare し、execute します。 影響を受けた行の数を、またエラーであれば undef を返します。 -1 は行の数が分からないか使用できないことを意味します。

This method is typically most useful for non-SELECT statements that either cannot be prepared in advance (due to a limitation of the driver) or do not need to be executed repeatedly. It should not be used for SELECT statements because it does not return a statement handle (so you can't fetch any data).

このメソッドは典型的には、(ドライバの制限により)前もって prepare されることが なかったり、繰り返し実行しない SELECT 以外 の文でとても有効です。 文ハンドルを返さない(そのために何もデータを取り出せない)ので、 SELECT 文では使うべきではありません。

The default do method is logically similar to:

デフォルトのdoメソッドは、論理的には以下のものと同様です:

  sub do {
      my($dbh, $statement, $attr, @bind_values) = @_;
      my $sth = $dbh->prepare($statement, $attr) or return undef;
      $sth->execute(@bind_values) or return undef;
      my $rows = $sth->rows;
      ($rows == 0) ? "0E0" : $rows; # always return true if no error
  }

For example:

例えば:

  my $rows_deleted = $dbh->do(q{
      DELETE FROM table
      WHERE status = ?
  }, undef, 'DONE') or die $dbh->errstr;

Using placeholders and @bind_values with the do method can be useful because it avoids the need to correctly quote any variables in the $statement. But if you'll be executing the statement many times then it's more efficient to prepare it once and call execute many times instead.

プレースホルダとバインド変数(@bind_values) を do メソッドで使うと、 $statement の中の変数を正しくクォートしなくてもよくなるためにとても 便利です。 しかしもし文を何度も実行するのであれば、代わりに 一度 prepare し、何度も execute するほうがより効率的です。

The q{...} style quoting used in this example avoids clashing with quotes that may be used in the SQL statement. Use the double-quote-like qq{...} operator if you want to interpolate variables into the string. See "Quote and Quote-like Operators" in perlop for more details.

この例で使われている q{ ...} 形式のクォートは、文で 使われているかもしれないクォートの対応を壊されないように使われています。 文字列に入っている変数を解釈したい場合には、ダブルクォート風 qq{...} 演算子を使います。 詳細は "Quote and Quote-like Operators" in perlop をご覧ください。

last_insert_id

  $rv = $dbh->last_insert_id($catalog, $schema, $table, $field);
  $rv = $dbh->last_insert_id($catalog, $schema, $table, $field, \%attr);

Returns a value 'identifying' the row just inserted, if possible. Typically this would be a value assigned by the database server to a column with an auto_increment or serial type. Returns undef if the driver does not support the method or can't determine the value.

Returns a value 'identifying' the row just inserted, if possible. Typically this would be a value assigned by the database server to a column with an auto_increment or serial type. Returns undef if the driver does not support the method or can't determine the value. (TBT)

The $catalog, $schema, $table, and $field parameters may be required for some drivers (see below). If you don't know the parameter values and your driver does not need them, then use undef for each.

The $catalog, $schema, $table, and $field parameters may be required for some drivers (see below). If you don't know the parameter values and your driver does not need them, then use undef for each. (TBT)

There are several caveats to be aware of with this method if you want to use it for portable applications:

このメソッドを移植性のあるアプリケーションに使いたいなら、注意するべき いくつかの警告があります:

* For some drivers the value may only available immediately after the insert statement has executed (e.g., mysql, Informix).

* ドライバによっては(mysql, Informix など)、値が insert 文が実行された 直後でのみ利用可能である場合があります。

* For some drivers the $catalog, $schema, $table, and $field parameters are required, for others they are ignored (e.g., mysql).

* ドライバによっては (mysql など)、$catalog, $schema, $table, $field パラメータが必要であったり、無視されたりします。

* Drivers may return an indeterminate value if no insert has been performed yet.

* insert 文がまだ実行されていない場合、ドライバは不定な値を 返すかもしれません。

* For some drivers the value may only be available if placeholders have not been used (e.g., Sybase, MS SQL). In this case the value returned would be from the last non-placeholder insert statement.

* For some drivers the value may only be available if placeholders have not been used (e.g., Sybase, MS SQL). In this case the value returned would be from the last non-placeholder insert statement. (TBT)

* Some drivers may need driver-specific hints about how to get the value. For example, being told the name of the database 'sequence' object that holds the value. Any such hints are passed as driver-specific attributes in the \%attr parameter.

* Some drivers may need driver-specific hints about how to get the value. For example, being told the name of the database 'sequence' object that holds the value. Any such hints are passed as driver-specific attributes in the \%attr parameter. (TBT)

* If the underlying database offers nothing better, then some drivers may attempt to implement this method by executing "select max($field) from $table". Drivers using any approach like this should issue a warning if AutoCommit is true because it is generally unsafe - another process may have modified the table between your insert and the select. For situations where you know it is safe, such as when you have locked the table, you can silence the warning by passing Warn => 0 in \%attr.

* If the underlying database offers nothing better, then some drivers may attempt to implement this method by executing "select max($field) from $table". Drivers using any approach like this should issue a warning if AutoCommit is true because it is generally unsafe - another process may have modified the table between your insert and the select. For situations where you know it is safe, such as when you have locked the table, you can silence the warning by passing Warn => 0 in \%attr. (TBT)

* If no insert has been performed yet, or the last insert failed, then the value is implementation defined.

* まだ insert 文が実行されていなかったり、最後の insert 文が 失敗していたりした場合、値は実装依存です。

Given all the caveats above, it's clear that this method must be used with care.

上述全ての注意点から、このメソッドは注意して使わなければならないことは 明らかです。

The last_insert_id method was added in DBI 1.38.

last_insert_id メソッドは DBI 1.38 で追加されました。

selectrow_array

  @row_ary = $dbh->selectrow_array($statement);
  @row_ary = $dbh->selectrow_array($statement, \%attr);
  @row_ary = $dbh->selectrow_array($statement, \%attr, @bind_values);

This utility method combines "prepare", "execute" and "fetchrow_array" into a single call. If called in a list context, it returns the first row of data from the statement. The $statement parameter can be a previously prepared statement handle, in which case the prepare is skipped.

このユーティリティーメソッドは、"prepare", "execute", "fetchrow_array" を一回にまとめておこないます。 リストコンテキストで呼ばれれば、その文によって返される 最初の行を返します。 $statement パラメータはすでに prepare されている 文ハンドルにすることができます。 その場合、prepare は飛ばされます。

If any method fails, and "RaiseError" is not set, selectrow_array will return an empty list.

いずれかのメソッドがエラーとなり、"RaiseError" が設定されていなければ、 selectrow_array は空のリストを返します。

If called in a scalar context for a statement handle that has more than one column, it is undefined whether the driver will return the value of the first column or the last. So don't do that. Also, in a scalar context, an undef is returned if there are no more rows or if an error occurred. That undef can't be distinguished from an undef returned because the first field value was NULL. For these reasons you should exercise some caution if you use selectrow_array in a scalar context, or just don't do that.

複数列のある文ハンドルに対してスカラコンテキストで呼び出すと、 ドライバが最初の列を返すか最後の列を返すかは未定義です。 従って、やってはいけません。 また、スカラコンテキストでは、 もう行がないかエラーが発生したならば、undef が返されます。 この undef は最初にフィールドの値が NULL であったために返された undef と区別することができません。 これらの理由によって、selectrow_array をスカラコンテキストで 呼び出すときには注意するか、単に使わないようにしてください。

selectrow_arrayref

  $ary_ref = $dbh->selectrow_arrayref($statement);
  $ary_ref = $dbh->selectrow_arrayref($statement, \%attr);
  $ary_ref = $dbh->selectrow_arrayref($statement, \%attr, @bind_values);

This utility method combines "prepare", "execute" and "fetchrow_arrayref" into a single call. It returns the first row of data from the statement. The $statement parameter can be a previously prepared statement handle, in which case the prepare is skipped.

This utility method combines "prepare", "execute" and "fetchrow_arrayref" into a single call. It returns the first row of data from the statement. The $statement parameter can be a previously prepared statement handle, in which case the prepare is skipped. (TBT)

If any method fails, and "RaiseError" is not set, selectrow_array will return undef.

いずれかのメソッドが失敗して、"RaiseError" がセットされていない場合は、 selectrow_array は undef を返します。

selectrow_hashref

  $hash_ref = $dbh->selectrow_hashref($statement);
  $hash_ref = $dbh->selectrow_hashref($statement, \%attr);
  $hash_ref = $dbh->selectrow_hashref($statement, \%attr, @bind_values);

This utility method combines "prepare", "execute" and "fetchrow_hashref" into a single call. It returns the first row of data from the statement. The $statement parameter can be a previously prepared statement handle, in which case the prepare is skipped.

This utility method combines "prepare", "execute" and "fetchrow_hashref" into a single call. It returns the first row of data from the statement. The $statement parameter can be a previously prepared statement handle, in which case the prepare is skipped. (TBT)

If any method fails, and "RaiseError" is not set, selectrow_hashref will return undef.

いずれかのメソッドが失敗して、"RaiseError" がセットされていない場合は、 selectrow_hashref は undef を返します。

selectall_arrayref

  $ary_ref = $dbh->selectall_arrayref($statement);
  $ary_ref = $dbh->selectall_arrayref($statement, \%attr);
  $ary_ref = $dbh->selectall_arrayref($statement, \%attr, @bind_values);

This utility method combines "prepare", "execute" and "fetchall_arrayref" into a single call. It returns a reference to an array containing a reference to an array (or hash, see below) for each row of data fetched.

このユーティリティメソッドは、"prepare", "execute", "fetchall_arrayref" を一回にまとめておこないます。 取り出されたデータの各行の配列(またはハッシュ; 後述)へのリファレンスが入った 配列へのリファレンスを返します。

The $statement parameter can be a previously prepared statement handle, in which case the prepare is skipped. This is recommended if the statement is going to be executed many times.

$statement パラメータを既に prepare されている文ハンドルに することができます。 その場合、prepare は飛ばされます。 これは何回も文が実行する予定であればお勧めです。

If "RaiseError" is not set and any method except fetchall_arrayref fails then selectall_arrayref will return undef; if fetchall_arrayref fails then it will return with whatever data has been fetched thus far. You should check $sth->err afterwards (or use the RaiseError attribute) to discover if the data is complete or was truncated due to an error.

If "RaiseError" is not set and any method except fetchall_arrayref fails then selectall_arrayref will return undef; if fetchall_arrayref fails then it will return with whatever data has been fetched thus far. You should check $sth->err afterwards (or use the RaiseError attribute) to discover if the data is complete or was truncated due to an error. (TBT)

The "fetchall_arrayref" method called by selectall_arrayref supports a $max_rows parameter. You can specify a value for $max_rows by including a 'MaxRows' attribute in \%attr. In which case finish() is called for you after fetchall_arrayref() returns.

The "fetchall_arrayref" method called by selectall_arrayref supports a $max_rows parameter. You can specify a value for $max_rows by including a 'MaxRows' attribute in \%attr. In which case finish() is called for you after fetchall_arrayref() returns. (TBT)

The "fetchall_arrayref" method called by selectall_arrayref also supports a $slice parameter. You can specify a value for $slice by including a 'Slice' or 'Columns' attribute in \%attr. The only difference between the two is that if Slice is not defined and Columns is an array ref, then the array is assumed to contain column index values (which count from 1), rather than perl array index values. In which case the array is copied and each value decremented before passing to /fetchall_arrayref.

The "fetchall_arrayref" method called by selectall_arrayref also supports a $slice parameter. You can specify a value for $slice by including a 'Slice' or 'Columns' attribute in \%attr. The only difference between the two is that if Slice is not defined and Columns is an array ref, then the array is assumed to contain column index values (which count from 1), rather than perl array index values. In which case the array is copied and each value decremented before passing to /fetchall_arrayref. (TBT)

You may often want to fetch an array of rows where each row is stored as a hash. That can be done simple using:

各行をハッシュとして保管している行の配列をフェッチしたいことが多いでしょう。 単純に以下のようにしてできます:

  my $emps = $dbh->selectall_arrayref(
      "SELECT ename FROM emp ORDER BY ename",
      { Slice => {} }
  );
  foreach my $emp ( @$emps ) {
      print "Employee: $emp->{ename}\n";
  }

Or, to fetch into an array instead of an array ref:

または、フェッチ内容を配列リファレンスではなく配列に入れるには:

  @result = @{ $dbh->selectall_arrayref($sql, { Slice => {} }) };

See "fetchall_arrayref" method for more details.

更なる詳細については "fetchall_arrayref" メソッドを参照してください。

selectall_hashref

  $hash_ref = $dbh->selectall_hashref($statement, $key_field);
  $hash_ref = $dbh->selectall_hashref($statement, $key_field, \%attr);
  $hash_ref = $dbh->selectall_hashref($statement, $key_field, \%attr, @bind_values);

This utility method combines "prepare", "execute" and "fetchall_hashref" into a single call. It returns a reference to a hash containing one entry, at most, for each row, as returned by fetchall_hashref().

This utility method combines "prepare", "execute" and "fetchall_hashref" into a single call. It returns a reference to a hash containing one entry, at most, for each row, as returned by fetchall_hashref(). (TBT)

The $statement parameter can be a previously prepared statement handle, in which case the prepare is skipped. This is recommended if the statement is going to be executed many times.

The $statement parameter can be a previously prepared statement handle, in which case the prepare is skipped. This is recommended if the statement is going to be executed many times. (TBT)

The $key_field parameter defines which column, or columns, are used as keys in the returned hash. It can either be the name of a single field, or a reference to an array containing multiple field names. Using multiple names yields a tree of nested hashes.

The $key_field parameter defines which column, or columns, are used as keys in the returned hash. It can either be the name of a single field, or a reference to an array containing multiple field names. Using multiple names yields a tree of nested hashes. (TBT)

If a row has the same key as an earlier row then it replaces the earlier row.

行が以前の行と同じキーの場合、以前の行は置き換えられます。

If any method except fetchrow_hashref fails, and "RaiseError" is not set, selectall_hashref will return undef. If fetchrow_hashref fails and "RaiseError" is not set, then it will return with whatever data it has fetched thus far. $DBI::err should be checked to catch that.

fetchrow_hashref 以外のいずれかのメソッドがエラーとなり、 "RaiseError" が設定されていなければ、selectall_hashrefundefを返します。 もし fetchrow_hashref が失敗し、"RaiseError" が設定されていなければ、 それまでに取り出したデータをなるべく多く返します。 それを捕らえるために $DBI::err をチェックすべきです。

See fetchall_hashref() for more details.

さらなる詳細については fetchall_hashref() を参照してください。

selectcol_arrayref

  $ary_ref = $dbh->selectcol_arrayref($statement);
  $ary_ref = $dbh->selectcol_arrayref($statement, \%attr);
  $ary_ref = $dbh->selectcol_arrayref($statement, \%attr, @bind_values);

This utility method combines "prepare", "execute", and fetching one column from all the rows, into a single call. It returns a reference to an array containing the values of the first column from each row.

このユーティリティーメソッドは、一回に "prepare", "execute" を まとめておこない、すべての行から一つのカラムからを取り出します。 各行からの最初のカラムの値が入った配列へのリファレンスを返します。

The $statement parameter can be a previously prepared statement handle, in which case the prepare is skipped. This is recommended if the statement is going to be executed many times.

$statement パラメータを既に prepare されている文ハンドルに することができます。 その場合、prepare は飛ばされます。 これは何回も文が実行する予定であればお勧めです。

If any method except fetch fails, and "RaiseError" is not set, selectcol_arrayref will return undef. If fetch fails and "RaiseError" is not set, then it will return with whatever data it has fetched thus far. $DBI::err should be checked to catch that.

fetch 以外のいずれかのメソッドがエラーとなり、"RaiseError" が 設定されていなければ、selectcol_arrayrefundef を返します。 もし fetch が失敗し、/RaiseError が設定されていなければ、それまでに 取り出したデータをなるべく多く返します。 それを捕らえるために $DBI::err をチェックすべきです。

The selectcol_arrayref method defaults to pushing a single column value (the first) from each row into the result array. However, it can also push another column, or even multiple columns per row, into the result array. This behaviour can be specified via a 'Columns' attribute which must be a ref to an array containing the column number or numbers to use. For example:

The selectcol_arrayref method defaults to pushing a single column value (the first) from each row into the result array. However, it can also push another column, or even multiple columns per row, into the result array. This behaviour can be specified via a 'Columns' attribute which must be a ref to an array containing the column number or numbers to use. For example: (TBT)

  # get array of id and name pairs:
  my $ary_ref = $dbh->selectcol_arrayref("select id, name from table", { Columns=>[1,2] });
  my %hash = @$ary_ref; # build hash from key-value pairs so $hash{$id} => name

You can specify a maximum number of rows to fetch by including a 'MaxRows' attribute in \%attr.

最大フェッチ行数は \%attr の 'MaxRows' 属性で指定できます。

prepare

  $sth = $dbh->prepare($statement)          or die $dbh->errstr;
  $sth = $dbh->prepare($statement, \%attr)  or die $dbh->errstr;

Prepares a statement for later execution by the database engine and returns a reference to a statement handle object.

一つの文を後でデータベースエンジンによって実行できるように準備し、 文ハンドルオブジェクトへのリファレンスを返します。

The returned statement handle can be used to get attributes of the statement and invoke the "execute" method. See "Statement Handle Methods".

返される文ハンドルは文の属性を取得したり、 "execute" メソッドの呼び出しに使われます。 "Statement Handle Methods" をご覧ください。

Drivers for engines without the concept of preparing a statement will typically just store the statement in the returned handle and process it when $sth->execute is called. Such drivers are unlikely to give much useful information about the statement, such as $sth->{NUM_OF_FIELDS}, until after $sth->execute has been called. Portable applications should take this into account.

準備された文という考えが無いドライバでは、通常、返される ハンドルに文を保存し、$sth->execute が呼ばれたらそれを 処理します。 そのようなドライバは $sth->{NUM_OF_FIELDS} のような 文について有効な情報を $sth->execute が呼ばれるまでは、 取得できることはまずありません。 移植可能なアプリケーションはこの点を注意する必要があります。

In general, DBI drivers do not parse the contents of the statement (other than simply counting any "Placeholders"). The statement is passed directly to the database engine, sometimes known as pass-thru mode. This has advantages and disadvantages. On the plus side, you can access all the functionality of the engine being used. On the downside, you're limited if you're using a simple engine, and you need to take extra care if writing applications intended to be portable between engines.

通常、DBIドライバは文を解析しません (そうでなければ単純にプレースホルダを数えます)。 文はデータベース・エンジンに直接渡されます、いわゆるパススルー モードです。 これは長所でも短所でもあります。 よく言えば、使われているエンジンのすべての機能にアクセスすることができます。 悪く言えば、簡単なエンジンを使っていれば制限されますし、エンジンをまたがって 移植可能なアプリケーションを書こうとすれば、非常に注意する必要があります。

Portable applications should not assume that a new statement can be prepared and/or executed while still fetching results from a previous statement.

移植可能なアプリケーションは、まだ前の文から結果を 取り出している間に、新しい文が prepare でき、そして/あるいは 実行できると想定するべきではありません。

Some command-line SQL tools use statement terminators, like a semicolon, to indicate the end of a statement. Such terminators should not normally be used with the DBI.

いくつかのコマンドライン型 SQL ツールは、セミコロンなどのステータスの終わりを 示すために、文末尾文字(statement terminator)を使っています。 通常そうした末尾文字を DBI で使われません。

prepare_cached

  $sth = $dbh->prepare_cached($statement)
  $sth = $dbh->prepare_cached($statement, \%attr)
  $sth = $dbh->prepare_cached($statement, \%attr, $if_active)

Like "prepare" except that the statement handle returned will be stored in a hash associated with the $dbh. If another call is made to prepare_cached with the same $statement and %attr parameter values, then the corresponding cached $sth will be returned without contacting the database server.

$dbh に関連付けられたハッシュに保存されることを除いて "prepare" と 同様です。 もし同じ $statement%attr パラメータの値ででもう一度 prepare_cached が呼び出されると、データベースサーバに コンタクトすることなく、対応する $sth が返されます。

The $if_active parameter lets you adjust the behaviour if an already cached statement handle is still Active. There are several alternatives:

The $if_active parameter lets you adjust the behaviour if an already cached statement handle is still Active. There are several alternatives: (TBT)

0: A warning will be generated, and finish() will be called on the statement handle before it is returned. This is the default behaviour if $if_active is not passed.
1: finish() will be called on the statement handle, but the warning is suppressed.
2: Disables any checking.
3: The existing active statement handle will be removed from the cache and a new statement handle prepared and cached in its place. This is the safest option because it doesn't affect the state of the old handle, it just removes it from the cache. [Added in DBI 1.40]

Here are some examples of prepare_cached:

以下は prepare_cached の例です:

  sub insert_hash {
    my ($table, $field_values) = @_;
    # sort to keep field order, and thus sql, stable for prepare_cached
    my @fields = sort keys %$field_values;
    my @values = @{$field_values}{@fields};
    my $sql = sprintf "insert into %s (%s) values (%s)",
        $table, join(",", @fields), join(",", ("?")x@fields);
    my $sth = $dbh->prepare_cached($sql);
    return $sth->execute(@values);
  }

  sub search_hash {
    my ($table, $field_values) = @_;
    # sort to keep field order, and thus sql, stable for prepare_cached
    my @fields = sort keys %$field_values;
    my @values = @{$field_values}{@fields};
    my $qualifier = "";
    $qualifier = "where ".join(" and ", map { "$_=?" } @fields) if @fields;
    $sth = $dbh->prepare_cached("SELECT * FROM $table $qualifier");
    return $dbh->selectall_arrayref($sth, {}, @values);
  }

Caveat emptor: This caching can be useful in some applications, but it can also cause problems and should be used with care. Here is a contrived case where caching would cause a significant problem:

Caveat emptor: This caching can be useful in some applications, but it can also cause problems and should be used with care. Here is a contrived case where caching would cause a significant problem: (TBT)

  my $sth = $dbh->prepare_cached('SELECT * FROM foo WHERE bar=?');
  $sth->execute(...);
  while (my $data = $sth->fetchrow_hashref) {

    # later, in some other code called within the loop...
    my $sth2 = $dbh->prepare_cached('SELECT * FROM foo WHERE bar=?');
    $sth2->execute(...);
    while (my $data2 = $sth2->fetchrow_arrayref) {
      do_stuff(...);
    }
  }

In this example, since both handles are preparing the exact same statement, $sth2 will not be its own statement handle, but a duplicate of $sth returned from the cache. The results will certainly not be what you expect. Typically the inner fetch loop will work normally, fetching all the records and terminating when there are no more, but now that $sth is the same as $sth2 the outer fetch loop will also terminate.

In this example, since both handles are preparing the exact same statement, $sth2 will not be its own statement handle, but a duplicate of $sth returned from the cache. The results will certainly not be what you expect. Typically the inner fetch loop will work normally, fetching all the records and terminating when there are no more, but now that $sth is the same as $sth2 the outer fetch loop will also terminate. (TBT)

You'll know if you run into this problem because prepare_cached() will generate a warning by default (when $if_active is false).

You'll know if you run into this problem because prepare_cached() will generate a warning by default (when $if_active is false). (TBT)

The cache used by prepare_cached() is keyed by both the statement and any attributes so you can also avoid this issue by doing something like:

The cache used by prepare_cached() is keyed by both the statement and any attributes so you can also avoid this issue by doing something like: (TBT)

  $sth = $dbh->prepare_cached("...", { dbi_dummy => __FILE__.__LINE__ });

which will ensure that prepare_cached only returns statements cached by that line of code in that source file.

which will ensure that prepare_cached only returns statements cached by that line of code in that source file. (TBT)

If you'd like the cache to managed intelligently, you can tie the hashref returned by CachedKids to an appropriate caching module, such as Tie::Cache::LRU:

If you'd like the cache to managed intelligently, you can tie the hashref returned by CachedKids to an appropriate caching module, such as Tie::Cache::LRU: (TBT)

  my $cache;
  tie %$cache, 'Tie::Cache::LRU', 500;
  $dbh->{CachedKids} = $cache;

commit

  $rc  = $dbh->commit     or die $dbh->errstr;

Commit (make permanent) the most recent series of database changes if the database supports transactions and AutoCommit is off.

データベースがトランザクションをサポートしていて AutoCommit がオフであれば、 データベースに対する直近の一連の変更をコミット(永続化)します。

If AutoCommit is on, then calling commit will issue a "commit ineffective with AutoCommit" warning.

AutoCommit がオンであれば、commit は "commit ineffective with AutoCommit" という警告を起こします。

See also "Transactions" in the "FURTHER INFORMATION" section below.

後述する "FURTHER INFORMATION" 章の "Transactions" も参照してください。

rollback

  $rc  = $dbh->rollback   or die $dbh->errstr;

Rollback (undo) the most recent series of uncommitted database changes if the database supports transactions and AutoCommit is off.

データベースがトランザクションをサポートしていて、AutoCommit がオフであれば、 データベースに対する直近の一連の変更をロールバックします(元に戻します)。

If AutoCommit is on, then calling rollback will issue a "rollback ineffective with AutoCommit" warning.

AutoCommit がオンであれば、rollback は "rollback ineffective with AutoCommit" という警告を起こします。

See also "Transactions" in the "FURTHER INFORMATION" section below.

後述する "FURTHER INFORMATION" 章の "Transactions" も参照してください。

begin_work

  $rc  = $dbh->begin_work   or die $dbh->errstr;

Enable transactions (by turning AutoCommit off) until the next call to commit or rollback. After the next commit or rollback, AutoCommit will automatically be turned on again.

Enable transactions (by turning AutoCommit off) until the next call to commit or rollback. After the next commit or rollback, AutoCommit will automatically be turned on again. (TBT)

If AutoCommit is already off when begin_work is called then it does nothing except return an error. If the driver does not support transactions then when begin_work attempts to set AutoCommit off the driver will trigger a fatal error.

If AutoCommit is already off when begin_work is called then it does nothing except return an error. If the driver does not support transactions then when begin_work attempts to set AutoCommit off the driver will trigger a fatal error. (TBT)

See also "Transactions" in the "FURTHER INFORMATION" section below.

後述する "FURTHER INFORMATION" 章の "Transactions" も参照してください。

disconnect

  $rc = $dbh->disconnect  or warn $dbh->errstr;

Disconnects the database from the database handle. disconnect is typically only used before exiting the program. The handle is of little use after disconnecting.

データベースハンドルをデータベースから切断します。 disconnect は普通プログラムを終了するときにだけ使います。 切断した後、ハンドルほとんど役に立ちません。

The transaction behaviour of the disconnect method is, sadly, undefined. Some database systems (such as Oracle and Ingres) will automatically commit any outstanding changes, but others (such as Informix) will rollback any outstanding changes. Applications not using AutoCommit should explicitly call commit or rollback before calling disconnect.

残念ながら disconnect メソッドにより、トランザクションがどうなるかは 決まっていません。 ある種のデータベースシステム(Oracle、Ingressなど)は自動的に変更を コミットしますが、(Infromixなど)変更をロールバックするものもあります。 AutoCommit を使わないアプリケーションは disconnect を呼び出す前に、 明確に commit または rollback を呼び出すべきです。

The database is automatically disconnected by the DESTROY method if still connected when there are no longer any references to the handle. The DESTROY method for each driver should implicitly call rollback to undo any uncommitted changes. This is vital behaviour to ensure that incomplete transactions don't get committed simply because Perl calls DESTROY on every object before exiting. Also, do not rely on the order of object destruction during "global destruction", as it is undefined.

まだ接続していて、ハンドルへの参照がまったくなくなった場合、 DESTROY メソッドによりデータベースは自動的に切断されます。 各ドライバへの DESTROY メソッドはコミットされていない変更を元に戻すため、 暗黙のうちに rollback を呼び出します。 これは終了する前に Perl が単に各オブジェクトに DESTROY を 呼び出すことによって、不完全なトランザクションがコミットされないということを 保証するためにきわめて重要です。 同様に「グローバルな破壊」でのオブジェクトの破壊の順序は信頼できません; これは未定義です。

Generally, if you want your changes to be committed or rolled back when you disconnect, then you should explicitly call "commit" or "rollback" before disconnecting.

一般的に、切断する前に変更をコミットまたはロールバックしたいのであれば、 切断する前に明示的に "commit" または "rollback" を呼び出すべきです。

If you disconnect from a database while you still have active statement handles (e.g., SELECT statement handles that may have more data to fetch), you will get a warning. The warning may indicate that a fetch loop terminated early, perhaps due to an uncaught error. To avoid the warning call the finish method on the active handles.

Active な文ハンドル(つまり、まだフェッチするデータがある SELECT 文 ハンドル)があるのにデータベースから切断すると警告を受けます。 警告はフェッチループが早く終わってしまったことを示していて、おそらくは 捕捉していないエラーによるものです。 警告を避けるには、アクティブハンドルに対して finish メソッドを 呼び出します。

ping

  $rc = $dbh->ping;

Attempts to determine, in a reasonably efficient way, if the database server is still running and the connection to it is still working. Individual drivers should implement this function in the most suitable manner for their database engine.

合理的で効率的な方法で、データベースサーバーが稼動しているか、接続が 動いているかを判定しようとします。各ドライバはこの関数をそれぞれの データベースに最も適切な方法で実装するべきです。

The current default implementation always returns true without actually doing anything. Actually, it returns "0 but true" which is true but zero. That way you can tell if the return value is genuine or just the default. Drivers should override this method with one that does the right thing for their type of database.

現在の デフォルトの 実装は、実際には何もせず常に真を返します。 実際には、それは「0 だが真」を返します; これは真ですが 0 です。 これにより返された値が本物なのか単なるデフォルトなのかがわかります。 ドライバはこのメソッドをデータベースのタイプにあったものでこのメソッドを 上書きしなければなりません。

Few applications would have direct use for this method. See the specialized Apache::DBI module for one example usage.

アプリケーションでこのメソッドを使うことはあまりないでしょう。 使用例としては専門的な Apache::DBI モジュールをご覧ください。

get_info

  $value = $dbh->get_info( $info_type );

Returns information about the implementation, i.e. driver and data source capabilities, restrictions etc. It returns undef for unknown or unimplemented information types. For example:

Returns information about the implementation, i.e. driver and data source capabilities, restrictions etc. It returns undef for unknown or unimplemented information types. For example: (TBT)

  $database_version  = $dbh->get_info(  18 ); # SQL_DBMS_VER
  $max_select_tables = $dbh->get_info( 106 ); # SQL_MAXIMUM_TABLES_IN_SELECT

See "Standards Reference Information" for more detailed information about the information types and their meanings and possible return values.

情報型とその意味およびあり得る返り値に関するさらに詳しい情報については "Standards Reference Information" を参照してください。

The DBI::Const::GetInfoType module exports a %GetInfoType hash that can be used to map info type names to numbers. For example:

DBI::Const::GetInfoType モジュールは、型名を数値にマッピングするために 使える %GetInfoType ハッシュをエクスポートします。 例えば:

  $database_version = $dbh->get_info( $GetInfoType{SQL_DBMS_VER} );

The names are a merging of the ANSI and ODBC standards (which differ in some cases). See DBI::Const::GetInfoType for more details.

名前は ANSI と ODBC の標準 (一部で異なります) をマージしたものです。 さらなる詳細については DBI::Const::GetInfoType を参照してください。

Because some DBI methods make use of get_info(), drivers are strongly encouraged to support at least the following very minimal set of information types to ensure the DBI itself works properly:

Because some DBI methods make use of get_info(), drivers are strongly encouraged to support at least the following very minimal set of information types to ensure the DBI itself works properly: (TBT)

 Type  Name                        Example A     Example B
 ----  --------------------------  ------------  ----------------
   17  SQL_DBMS_NAME               'ACCESS'      'Oracle'
   18  SQL_DBMS_VER                '03.50.0000'  '08.01.0721 ...'
   29  SQL_IDENTIFIER_QUOTE_CHAR   '`'           '"'
   41  SQL_CATALOG_NAME_SEPARATOR  '.'           '@'
  114  SQL_CATALOG_LOCATION        1             2

table_info

  $sth = $dbh->table_info( $catalog, $schema, $table, $type );
  $sth = $dbh->table_info( $catalog, $schema, $table, $type, \%attr );

  # then $sth->fetchall_arrayref or $sth->fetchall_hashref etc

Returns an active statement handle that can be used to fetch information about tables and views that exist in the database.

データベースに存在するテーブルやビューの情報を取得するために使われる Active な文・ハンドルを返します。

The arguments $catalog, $schema and $table may accept search patterns according to the database/driver, for example: $table = '%FOO%'; Remember that the underscore character ('_') is a search pattern that means match any character, so 'FOO_%' is the same as 'FOO%' and 'FOO_BAR%' will match names like 'FOO1BAR'.

引数 $catalog, $schema, $table はデータベース/ドライバによって検索 パターンを受け取るかもしれません。 例えば: $table = '%FOO%'; 下線文字 ('_') は任意の文字を意味する検索パターンを意味するので、 'FOO_%' は 'FOO%' と同じで、'FOO_BAR%' は 'FOO1BAR' のような名前に マッチングするということに注意してください。

The value of $type is a comma-separated list of one or more types of tables to be returned in the result set. Each value may optionally be quoted, e.g.:

$type の値は結果セットで返されるーブルの一つまたは複数のデータ型のカンマ 区切りのリストです。 それぞれの値はオプションでクォートされるかもしれません; 例えば:

  $type = "TABLE";
  $type = "'TABLE','VIEW'";

In addition the following special cases may also be supported by some drivers:

さらにドライバによっては以下の特殊なケースもサポートされているかもしれません。

  • If the value of $catalog is '%' and $schema and $table name are empty strings, the result set contains a list of catalog names. For example:

    $catalog の値が '%' で $schema と $table が空文字列であれば、結果セットには カタログ名のリストが入ります。 例えば:

      $sth = $dbh->table_info('%', '', '');
  • If the value of $schema is '%' and $catalog and $table are empty strings, the result set contains a list of schema names.

    $schema の値が '%' で $catalog と $table が空文字列であれば、結果セットには スキーマ名のリストが入ります。

  • If the value of $type is '%' and $catalog, $schema, and $table are all empty strings, the result set contains a list of table types.

    $type の値が '%' で $catalog, $schema, $table がすべて空文字列であれば、 結果セットにはテーブル・タイプのリストが入ります。

If your driver doesn't support one or more of the selection filter parameters then you may get back more than you asked for and can do the filtering yourself.

If your driver doesn't support one or more of the selection filter parameters then you may get back more than you asked for and can do the filtering yourself. (TBT)

This method can be expensive, and can return a large amount of data. (For example, small Oracle installation returns over 2000 rows.) So it's a good idea to use the filters to limit the data as much as possible.

This method can be expensive, and can return a large amount of data. (For example, small Oracle installation returns over 2000 rows.) So it's a good idea to use the filters to limit the data as much as possible. (TBT)

The statement handle returned has at least the following fields in the order show below. Other fields, after these, may also be present.

返された行ハンドルは少なくとも後述する順序で以下のフィールドを持ちます。 これらの後に、他のフィールドもあるかもしれません。

TABLE_CAT: Table catalog identifier. This field is NULL (undef) if not applicable to the data source, which is usually the case. This field is empty if not applicable to the table.

TABLE_CAT: テーブル・カタログ識別子。 通常そうなのですが、データソースに適用できなければ、このフィールドが NULL(undef)です。 テーブルに適用できなければ、このフィールドは空です。

TABLE_SCHEM: The name of the schema containing the TABLE_NAME value. This field is NULL (undef) if not applicable to data source, and empty if not applicable to the table.

TABLE_SCHEM: TABLE_NAME値が入っているスキーマの名前です。 データソースに適用できなければ、このフィールドがNULL(undef)です。 テーブルに適用できなければ、このフィールドは空です。

TABLE_NAME: Name of the table (or view, synonym, etc).

TABLE_NAME: テーブル(またはビュー、シノニムなど)の名前。

TABLE_TYPE: One of the following: "TABLE", "VIEW", "SYSTEM TABLE", "GLOBAL TEMPORARY", "LOCAL TEMPORARY", "ALIAS", "SYNONYM" or a type identifier that is specific to the data source.

TABLE_TYPE: TABLE", "VIEW", "SYSTEM TABLE", "GLOBAL TEMPORARY", "LOCAL TEMPORARY", "ALIAS", "SYNONYM" または そのデータソース独自の型識別子のいずれか。

REMARKS: A description of the table. May be NULL (undef).

REMARKS: テーブルの説明。NULL(undef)かもしれません。

Note that table_info might not return records for all tables. Applications can use any valid table regardless of whether it's returned by table_info.

table_info がすべてのテーブルについてレコードを返さないかもしれないことに 注意してください。 table_info により返されたかどうかに関係無く、アプリケーションではすべての 適正なテーブルを扱うことができます。

"tables", "Catalog Methods", "Standards Reference Information" も 参照してください。

column_info

  $sth = $dbh->column_info( $catalog, $schema, $table, $column );

  # then $sth->fetchall_arrayref or $sth->fetchall_hashref etc

Returns an active statement handle that can be used to fetch information about columns in specified tables.

指定された表の行について情報を得るために使える有効な文ハンドルを返します。

The arguments $schema, $table and $column may accept search patterns according to the database/driver, for example: $table = '%FOO%';

引数 $schema, $table, $column はデータベース/ドライバによる検索パターンを 受け付けます; 例えば: $table = '%FOO%';

Note: The support for the selection criteria is driver specific. If the driver doesn't support one or more of them then you may get back more than you asked for and can do the filtering yourself.

Note: The support for the selection criteria is driver specific. If the driver doesn't support one or more of them then you may get back more than you asked for and can do the filtering yourself. (TBT)

Note: If your driver does not support column_info an undef is returned. This is distinct from asking for something which does not exist in a driver which supports column_info as a valid statement handle to an empty result-set will be returned in this case.

Note: If your driver does not support column_info an undef is returned. This is distinct from asking for something which does not exist in a driver which supports column_info as a valid statement handle to an empty result-set will be returned in this case. (TBT)

If the arguments don't match any tables then you'll still get a statement handle, it'll just return no rows.

引数がどの表にもマッチングしない場合、単に何の行も返さない 文ハンドルが得られます。

The statement handle returned has at least the following fields in the order shown below. Other fields, after these, may also be present.

返された行ハンドルは少なくとも後述する順序で以下のフィールドを持ちます。 これらの後に、他のフィールドもあるかもしれません。

TABLE_CAT: The catalog identifier. This field is NULL (undef) if not applicable to the data source, which is often the case. This field is empty if not applicable to the table.

TABLE_CAT: The catalog identifier. This field is NULL (undef) if not applicable to the data source, which is often the case. This field is empty if not applicable to the table. (TBT)

TABLE_SCHEM: The schema identifier. This field is NULL (undef) if not applicable to the data source, and empty if not applicable to the table.

TABLE_SCHEM: The schema identifier. This field is NULL (undef) if not applicable to the data source, and empty if not applicable to the table. (TBT)

TABLE_NAME: The table identifier. Note: A driver may provide column metadata not only for base tables, but also for derived objects like SYNONYMS etc.

TABLE_NAME: The table identifier. Note: A driver may provide column metadata not only for base tables, but also for derived objects like SYNONYMS etc. (TBT)

COLUMN_NAME: The column identifier.

COLUMN_NAME: 列識別子。

DATA_TYPE: The concise data type code.

DATA_TYPE: 簡潔なデータ型コード。

TYPE_NAME: A data source dependent data type name.

TYPE_NAME: データソース依存のデータ型名。

COLUMN_SIZE: The column size. This is the maximum length in characters for character data types, the number of digits or bits for numeric data types or the length in the representation of temporal types. See the relevant specifications for detailed information.

COLUMN_SIZE: The column size. This is the maximum length in characters for character data types, the number of digits or bits for numeric data types or the length in the representation of temporal types. See the relevant specifications for detailed information. (TBT)

BUFFER_LENGTH: The length in bytes of transferred data.

BUFFER_LENGTH: 転送されたデータのバイト数。

DECIMAL_DIGITS: The total number of significant digits to the right of the decimal point.

DECIMAL_DIGITS: 小数点の右側の有効桁数。

NUM_PREC_RADIX: The radix for numeric precision. The value is 10 or 2 for numeric data types and NULL (undef) if not applicable.

NUM_PREC_RADIX: The radix for numeric precision. The value is 10 or 2 for numeric data types and NULL (undef) if not applicable. (TBT)

NULLABLE: Indicates if a column can accept NULLs. The following values are defined:

NULLABLE: 列が NULL を受け付けるかを示す。 以下の値が定義されています:

  SQL_NO_NULLS          0
  SQL_NULLABLE          1
  SQL_NULLABLE_UNKNOWN  2

REMARKS: A description of the column.

REMARKS: 列の説明。

COLUMN_DEF: The default value of the column, in a format that can be used directly in an SQL statement.

COLUMN_DEF: SQL に直接使える形での、列のデフォルト値。

Note that this may be an expression and not simply the text used for the default value in the original CREATE TABLE statement. For example, given:

これは式になって、元の CREATE TABLE 文のデフォルトとして使われた単純な テキストではないかもしれないことに注意してください。 例えば、以下のようにすると:

    col1 char(30) default current_user    -- a 'function'
    col2 char(30) default 'string'        -- a string literal

where "current_user" is the name of a function, the corresponding COLUMN_DEF values would be:

ここで "current_user" が関数名とすると、対応する COLUMN_DEF の値は 以下のようになります:

    Database        col1                     col2
    --------        ----                     ----
    Oracle:         current_user             'string'
    Postgres:       "current_user"()         'string'::text
    MS SQL:         (user_name())            ('string')

SQL_DATA_TYPE: The SQL data type.

SQL_DATA_TYPE: SQL データ型。

SQL_DATETIME_SUB: The subtype code for datetime and interval data types.

SQL_DATETIME_SUB: 日付時刻と内部データ型のためのサブ型コード。

CHAR_OCTET_LENGTH: The maximum length in bytes of a character or binary data type column.

CHAR_OCTET_LENGTH: 文字やバイナリデータ型列の最大バイト長。

ORDINAL_POSITION: The column sequence number (starting with 1).

ORDINAL_POSITION: 列シーケンス番号 (1 から開始)。

IS_NULLABLE: Indicates if the column can accept NULLs. Possible values are: 'NO', 'YES' and ''.

IS_NULLABLE: 列が NULL を受け付けるかを示す。 取り得る値は: 'NO', 'YES', ''.

SQL/CLI defines the following additional columns:

SQL/CLI は以下の追加の列を定義しています:

  CHAR_SET_CAT
  CHAR_SET_SCHEM
  CHAR_SET_NAME
  COLLATION_CAT
  COLLATION_SCHEM
  COLLATION_NAME
  UDT_CAT
  UDT_SCHEM
  UDT_NAME
  DOMAIN_CAT
  DOMAIN_SCHEM
  DOMAIN_NAME
  SCOPE_CAT
  SCOPE_SCHEM
  SCOPE_NAME
  MAX_CARDINALITY
  DTD_IDENTIFIER
  IS_SELF_REF

Drivers capable of supplying any of those values should do so in the corresponding column and supply undef values for the others.

Drivers capable of supplying any of those values should do so in the corresponding column and supply undef values for the others. (TBT)

Drivers wishing to provide extra database/driver specific information should do so in extra columns beyond all those listed above, and use lowercase field names with the driver-specific prefix (i.e., 'ora_...'). Applications accessing such fields should do so by name and not by column number.

Drivers wishing to provide extra database/driver specific information should do so in extra columns beyond all those listed above, and use lowercase field names with the driver-specific prefix (i.e., 'ora_...'). Applications accessing such fields should do so by name and not by column number. (TBT)

The result set is ordered by TABLE_CAT, TABLE_SCHEM, TABLE_NAME and ORDINAL_POSITION.

結果セットは TABLE_CAT, TABLE_SCHEM, TABLE_NAME, ORDINAL_POSITION で ソートされます。

Note: There is some overlap with statement handle attributes (in perl) and SQLDescribeCol (in ODBC). However, SQLColumns provides more metadata.

注意: (perl での)文ハンドル属性と (ODBC での) SQLDescribeCol には 重複があります。 しかし、SQLDescribeCol はさらなるメタデータを提供します。

"Catalog Methods""Standards Reference Information" も 参照してください。

primary_key_info

  $sth = $dbh->primary_key_info( $catalog, $schema, $table );

  # then $sth->fetchall_arrayref or $sth->fetchall_hashref etc

Returns an active statement handle that can be used to fetch information about columns that make up the primary key for a table. The arguments don't accept search patterns (unlike table_info()).

テーブルのための主キーとして設定されているカラムについての情報を 取り出すために使われる Active な文・ハンドルを返します。 引数に検索パターンは受け取りません(table_info()とは違って)。

The statement handle will return one row per column, ordered by TABLE_CAT, TABLE_SCHEM, TABLE_NAME, and KEY_SEQ. If there is no primary key then the statement handle will fetch no rows.

The statement handle will return one row per column, ordered by TABLE_CAT, TABLE_SCHEM, TABLE_NAME, and KEY_SEQ. If there is no primary key then the statement handle will fetch no rows. (TBT)

Note: The support for the selection criteria, such as $catalog, is driver specific. If the driver doesn't support catalogs and/or schemas, it may ignore these criteria.

注意:$catalog のような、選択条件のサポートはドライバによります。 もしドライバがカタログやスキーマをサポートしていなければ、これらの条件は 無視されるかもしれません。

The statement handle returned has at least the following fields in the order shown below. Other fields, after these, may also be present.

返された行ハンドルは少なくとも後述する順序で以下のフィールドを持ちます。 これらの後に、他のフィールドもあるかもしれません。

TABLE_CAT: The catalog identifier. This field is NULL (undef) if not applicable to the data source, which is often the case. This field is empty if not applicable to the table.

TABLE_CAT: カタログ識別子。 よくあることですが、データソースに適用できなければ、このフィールドが NULL(undef)です。 テーブルに適用できなければ、このフィールドは空です。

TABLE_SCHEM: The schema identifier. This field is NULL (undef) if not applicable to the data source, and empty if not applicable to the table.

TABLE_SCHEM: スキーマ識別子。 データソースに適用できなければ、このフィールドがNULL(undef)です。 テーブルに適用できなければ、このフィールドは空です。

TABLE_NAME: The table identifier.

TABLE_NAME: テーブル識別子。

COLUMN_NAME: The column identifier.

COLUMN_NAME: カラム識別子。

KEY_SEQ: The column sequence number (starting with 1). Note: This field is named ORDINAL_POSITION in SQL/CLI.

KEY_SEQ: カラム順序番号(1始まり)。 注意:SQL/CLI ではこのフィールドは ORDINAL_POSITION と名づけられています。

PK_NAME: The primary key constraint identifier. This field is NULL (undef) if not applicable to the data source.

PK_NAME: 主キー制約識別子。 データソースに適用できなければ NULL(undef) です。

"Catalog Methods""Standards Reference Information" も 参照してください。

primary_key

  @key_column_names = $dbh->primary_key( $catalog, $schema, $table );

Simple interface to the primary_key_info() method. Returns a list of the column names that comprise the primary key of the specified table. The list is in primary key column sequence order. If there is no primary key then an empty list is returned.

primary_key_info() メソッドへの単純なインターフェースです。 指定されたテーブルの主キーを含むカラム目のリストを返します。 このリストは主キーカラム順番号順に入ります。 主キーがない場合、空リストが返されます。

foreign_key_info

  $sth = $dbh->foreign_key_info( $pk_catalog, $pk_schema, $pk_table
                               , $fk_catalog, $fk_schema, $fk_table );

  $sth = $dbh->foreign_key_info( $pk_catalog, $pk_schema, $pk_table
                               , $fk_catalog, $fk_schema, $fk_table
                               , \%attr );

  # then $sth->fetchall_arrayref or $sth->fetchall_hashref etc

Returns an active statement handle that can be used to fetch information about foreign keys in and/or referencing the specified table(s). The arguments don't accept search patterns (unlike table_info()).

Returns an active statement handle that can be used to fetch information about foreign keys in and/or referencing the specified table(s). The arguments don't accept search patterns (unlike table_info()). (TBT)

$pk_catalog, $pk_schema, $pk_table identify the primary (unique) key table (PKT).

$pk_catalog, $pk_schema, $pk_table は主(ユニーク)キー表 (PKT) を識別します。

$fk_catalog, $fk_schema, $fk_table identify the foreign key table (FKT).

$fk_catalog, $fk_schema, $fk_table は外部キー表 (FKT) を 識別します。

If both PKT and FKT are given, the function returns the foreign key, if any, in table FKT that refers to the primary (unique) key of table PKT. (Note: In SQL/CLI, the result is implementation-defined.)

If both PKT and FKT are given, the function returns the foreign key, if any, in table FKT that refers to the primary (unique) key of table PKT. (Note: In SQL/CLI, the result is implementation-defined.) (TBT)

If only PKT is given, then the result set contains the primary key of that table and all foreign keys that refer to it.

PKT のみが指定されると、結果セットにはその表の主キーと、それを 参照している全ての外部キーが含まれます。

If only FKT is given, then the result set contains all foreign keys in that table and the primary keys to which they refer. (Note: In SQL/CLI, the result includes unique keys too.)

If only FKT is given, then the result set contains all foreign keys in that table and the primary keys to which they refer. (Note: In SQL/CLI, the result includes unique keys too.) (TBT)

For example:

例えば:

  $sth = $dbh->foreign_key_info( undef, $user, 'master');
  $sth = $dbh->foreign_key_info( undef, undef,   undef , undef, $user, 'detail');
  $sth = $dbh->foreign_key_info( undef, $user, 'master', undef, $user, 'detail');

  # then $sth->fetchall_arrayref or $sth->fetchall_hashref etc

Note: The support for the selection criteria, such as $catalog, is driver specific. If the driver doesn't support catalogs and/or schemas, it may ignore these criteria.

Note: The support for the selection criteria, such as $catalog, is driver specific. If the driver doesn't support catalogs and/or schemas, it may ignore these criteria. (TBT)

The statement handle returned has the following fields in the order shown below. Because ODBC never includes unique keys, they define different columns in the result set than SQL/CLI. SQL/CLI column names are shown in parentheses.

The statement handle returned has the following fields in the order shown below. Because ODBC never includes unique keys, they define different columns in the result set than SQL/CLI. SQL/CLI column names are shown in parentheses. (TBT)

PKTABLE_CAT ( UK_TABLE_CAT ): The primary (unique) key table catalog identifier. This field is NULL (undef) if not applicable to the data source, which is often the case. This field is empty if not applicable to the table.

PKTABLE_CAT ( UK_TABLE_CAT ): The primary (unique) key table catalog identifier. This field is NULL (undef) if not applicable to the data source, which is often the case. This field is empty if not applicable to the table. (TBT)

PKTABLE_SCHEM ( UK_TABLE_SCHEM ): The primary (unique) key table schema identifier. This field is NULL (undef) if not applicable to the data source, and empty if not applicable to the table.

PKTABLE_SCHEM ( UK_TABLE_SCHEM ): The primary (unique) key table schema identifier. This field is NULL (undef) if not applicable to the data source, and empty if not applicable to the table. (TBT)

PKTABLE_NAME ( UK_TABLE_NAME ): The primary (unique) key table identifier.

PKTABLE_NAME ( UK_TABLE_NAME ): 主(ユニーク)キー表識別子。

PKCOLUMN_NAME (UK_COLUMN_NAME ): The primary (unique) key column identifier.

PKCOLUMN_NAME (UK_COLUMN_NAME ): 主(ユニーク)キー列識別子。

FKTABLE_CAT ( FK_TABLE_CAT ): The foreign key table catalog identifier. This field is NULL (undef) if not applicable to the data source, which is often the case. This field is empty if not applicable to the table.

FKTABLE_CAT ( FK_TABLE_CAT ): The foreign key table catalog identifier. This field is NULL (undef) if not applicable to the data source, which is often the case. This field is empty if not applicable to the table. (TBT)

FKTABLE_SCHEM ( FK_TABLE_SCHEM ): The foreign key table schema identifier. This field is NULL (undef) if not applicable to the data source, and empty if not applicable to the table.

FKTABLE_SCHEM ( FK_TABLE_SCHEM ): The foreign key table schema identifier. This field is NULL (undef) if not applicable to the data source, and empty if not applicable to the table. (TBT)

FKTABLE_NAME ( FK_TABLE_NAME ): The foreign key table identifier.

FKTABLE_NAME ( FK_TABLE_NAME ): 外部キー表識別子。

FKCOLUMN_NAME ( FK_COLUMN_NAME ): The foreign key column identifier.

FKCOLUMN_NAME ( FK_COLUMN_NAME ): 外部キー列識別子。

KEY_SEQ ( ORDINAL_POSITION ): The column sequence number (starting with 1).

KEY_SEQ ( ORDINAL_POSITION ): 列シーケンス番号(1 から開始)。

UPDATE_RULE ( UPDATE_RULE ): The referential action for the UPDATE rule. The following codes are defined:

UPDATE_RULE ( UPDATE_RULE ): The referential action for the UPDATE rule. The following codes are defined: (TBT)

  CASCADE              0
  RESTRICT             1
  SET NULL             2
  NO ACTION            3
  SET DEFAULT          4

DELETE_RULE ( DELETE_RULE ): The referential action for the DELETE rule. The codes are the same as for UPDATE_RULE.

DELETE_RULE ( DELETE_RULE ): The referential action for the DELETE rule. The codes are the same as for UPDATE_RULE. (TBT)

FK_NAME ( FK_NAME ): The foreign key name.

FK_NAME ( FK_NAME ): 外部キー名。

PK_NAME ( UK_NAME ): The primary (unique) key name.

PK_NAME ( UK_NAME ): 主 (ユニーク) キー名。

DEFERRABILITY ( DEFERABILITY ): The deferrability of the foreign key constraint. The following codes are defined:

DEFERRABILITY ( DEFERABILITY ): The deferrability of the foreign key constraint. The following codes are defined: (TBT)

  INITIALLY DEFERRED   5
  INITIALLY IMMEDIATE  6
  NOT DEFERRABLE       7

( UNIQUE_OR_PRIMARY ): This column is necessary if a driver includes all candidate (i.e. primary and alternate) keys in the result set (as specified by SQL/CLI). The value of this column is UNIQUE if the foreign key references an alternate key and PRIMARY if the foreign key references a primary key, or it may be undefined if the driver doesn't have access to the information.

( UNIQUE_OR_PRIMARY ): This column is necessary if a driver includes all candidate (i.e. primary and alternate) keys in the result set (as specified by SQL/CLI). The value of this column is UNIQUE if the foreign key references an alternate key and PRIMARY if the foreign key references a primary key, or it may be undefined if the driver doesn't have access to the information. (TBT)

"Catalog Methods""Standards Reference Information" も 参照してください。

statistics_info

Warning: This method is experimental and may change.

警告: このメソッドは実験的であり変更されるかもしれません。

  $sth = $dbh->statistics_info( $catalog, $schema, $table, $unique_only, $quick );

  # then $sth->fetchall_arrayref or $sth->fetchall_hashref etc

Returns an active statement handle that can be used to fetch statistical information about a table and its indexes.

表とそのインデックスに関する統計情報を取得するのに使える、有効な 文ハンドルを返します。

The arguments don't accept search patterns (unlike "table_info").

引数は ("table_info" と違って) 検索パターンは受け付けません。

If the boolean argument $unique_only is true, only UNIQUE indexes will be returned in the result set, otherwise all indexes will be returned.

真偽値引数 $unique_only が真なら、ユニークインデックスのみが 結果セットで返され、さもなければ全てのインデックスが返されます。

If the boolean argument $quick is set, the actual statistical information columns (CARDINALITY and PAGES) will only be returned if they are readily available from the server, and might not be current. Some databases may return stale statistics or no statistics at all with this flag set.

If the boolean argument $quick is set, the actual statistical information columns (CARDINALITY and PAGES) will only be returned if they are readily available from the server, and might not be current. Some databases may return stale statistics or no statistics at all with this flag set. (TBT)

The statement handle will return at most one row per column name per index, plus at most one row for the entire table itself, ordered by NON_UNIQUE, TYPE, INDEX_QUALIFIER, INDEX_NAME, and ORDINAL_POSITION.

The statement handle will return at most one row per column name per index, plus at most one row for the entire table itself, ordered by NON_UNIQUE, TYPE, INDEX_QUALIFIER, INDEX_NAME, and ORDINAL_POSITION. (TBT)

Note: The support for the selection criteria, such as $catalog, is driver specific. If the driver doesn't support catalogs and/or schemas, it may ignore these criteria.

Note: The support for the selection criteria, such as $catalog, is driver specific. If the driver doesn't support catalogs and/or schemas, it may ignore these criteria. (TBT)

The statement handle returned has at least the following fields in the order shown below. Other fields, after these, may also be present.

返された行ハンドルは少なくとも後述する順序で以下のフィールドを持ちます。 これらの後に、他のフィールドもあるかもしれません。

TABLE_CAT: The catalog identifier. This field is NULL (undef) if not applicable to the data source, which is often the case. This field is empty if not applicable to the table.

TABLE_CAT: The catalog identifier. This field is NULL (undef) if not applicable to the data source, which is often the case. This field is empty if not applicable to the table. (TBT)

TABLE_SCHEM: The schema identifier. This field is NULL (undef) if not applicable to the data source, and empty if not applicable to the table.

TABLE_SCHEM: The schema identifier. This field is NULL (undef) if not applicable to the data source, and empty if not applicable to the table. (TBT)

TABLE_NAME: The table identifier.

TABLE_NAME: テーブル識別子。

NON_UNIQUE: Unique index indicator. Returns 0 for unique indexes, 1 for non-unique indexes

NON_UNIQUE: ユニークインデックス指示子。 ユニークインデックスの場合は 0 を、それ以外のインデックスでは 1 を 返します。

INDEX_QUALIFIER: Index qualifier identifier. The identifier that is used to qualify the index name when doing a DROP INDEX; NULL (undef) is returned if an index qualifier is not supported by the data source. If a non-NULL (defined) value is returned in this column, it must be used to qualify the index name on a DROP INDEX statement; otherwise, the TABLE_SCHEM should be used to qualify the index name.

INDEX_QUALIFIER: Index qualifier identifier. The identifier that is used to qualify the index name when doing a DROP INDEX; NULL (undef) is returned if an index qualifier is not supported by the data source. If a non-NULL (defined) value is returned in this column, it must be used to qualify the index name on a DROP INDEX statement; otherwise, the TABLE_SCHEM should be used to qualify the index name. (TBT)

INDEX_NAME: The index identifier.

INDEX_NAME: インデックス識別子。

TYPE: The type of information being returned. Can be any of the following values: 'table', 'btree', 'clustered', 'content', 'hashed', or 'other'.

TYPE: The type of information being returned. Can be any of the following values: 'table', 'btree', 'clustered', 'content', 'hashed', or 'other'. (TBT)

In the case that this field is 'table', all fields other than TABLE_CAT, TABLE_SCHEM, TABLE_NAME, TYPE, CARDINALITY, and PAGES will be NULL (undef).

In the case that this field is 'table', all fields other than TABLE_CAT, TABLE_SCHEM, TABLE_NAME, TYPE, CARDINALITY, and PAGES will be NULL (undef). (TBT)

ORDINAL_POSITION: Column sequence number (starting with 1).

ORDINAL_POSITION: 列シーケンス番号 (1 から開始)。

COLUMN_NAME: The column identifier.

COLUMN_NAME: 列識別子。

ASC_OR_DESC: Column sort sequence. A for Ascending, D for Descending, or NULL (undef) if not supported for this index.

ASC_OR_DESC: Column sort sequence. A for Ascending, D for Descending, or NULL (undef) if not supported for this index. (TBT)

CARDINALITY: Cardinality of the table or index. For indexes, this is the number of unique values in the index. For tables, this is the number of rows in the table. If not supported, the value will be NULL (undef).

CARDINALITY: Cardinality of the table or index. For indexes, this is the number of unique values in the index. For tables, this is the number of rows in the table. If not supported, the value will be NULL (undef). (TBT)

PAGES: Number of storage pages used by this table or index. If not supported, the value will be NULL (undef).

PAGES: この表またはインデックスで使われるページ番号。 対応していない場合は、値は NULL (undef) になります。

FILTER_CONDITION: The index filter condition as a string. If the index is not a filtered index, or it cannot be determined whether the index is a filtered index, this value is NULL (undef). If the index is a filtered index, but the filter condition cannot be determined, this value is the empty string ''. Otherwise it will be the literal filter condition as a string, such as SALARY <= 4500.

FILTER_CONDITION: The index filter condition as a string. If the index is not a filtered index, or it cannot be determined whether the index is a filtered index, this value is NULL (undef). If the index is a filtered index, but the filter condition cannot be determined, this value is the empty string ''. Otherwise it will be the literal filter condition as a string, such as SALARY <= 4500. (TBT)

"Catalog Methods""Standards Reference Information" も 参照してください。

tables

  @names = $dbh->tables( $catalog, $schema, $table, $type );
  @names = $dbh->tables;        # deprecated

Simple interface to table_info(). Returns a list of matching table names, possibly including a catalog/schema prefix.

table_info()への単純なインターフェースです。 テーブル、ビューの名前の単純なリストを返します; おそらく頭にスキーマがついてきます。

See "table_info" for a description of the parameters.

パラメータの説明については "table_info" を参照してください。

If $dbh->get_info(29) returns true (29 is SQL_IDENTIFIER_QUOTE_CHAR) then the table names are constructed and quoted by "quote_identifier" to ensure they are usable even if they contain whitespace or reserved words etc. This means that the table names returned will include quote characters.

If $dbh->get_info(29) returns true (29 is SQL_IDENTIFIER_QUOTE_CHAR) then the table names are constructed and quoted by "quote_identifier" to ensure they are usable even if they contain whitespace or reserved words etc. This means that the table names returned will include quote characters. (TBT)

type_info_all

  $type_info_all = $dbh->type_info_all;

Returns a reference to an array which holds information about each data type variant supported by the database and driver. The array and its contents should be treated as read-only.

データベースあるいはドライバによりサポートされるデータ型についての情報が 入った配列へのリファレンスを返します。 配列及びその内容は読み込み専用として扱われなければなりません。

The first item is a reference to an 'index' hash of Name => Index pairs. The items following that are references to arrays, one per supported data type variant. The leading index hash defines the names and order of the fields within the arrays that follow it. For example:

最初の要素は 名前 = > インデックスというペアのハッシュへの リファレンスです。 その後の要素は、配列へのリファレンスで、1つずつがサポートされている データ型になります。 最初のハッシュが後に続く配列要素のフィールドの名前と順序を定義しています。 例:

  $type_info_all = [
    {   TYPE_NAME         => 0,
        DATA_TYPE         => 1,
        COLUMN_SIZE       => 2,     # was PRECISION originally
        LITERAL_PREFIX    => 3,
        LITERAL_SUFFIX    => 4,
        CREATE_PARAMS     => 5,
        NULLABLE          => 6,
        CASE_SENSITIVE    => 7,
        SEARCHABLE        => 8,
        UNSIGNED_ATTRIBUTE=> 9,
        FIXED_PREC_SCALE  => 10,    # was MONEY originally
        AUTO_UNIQUE_VALUE => 11,    # was AUTO_INCREMENT originally
        LOCAL_TYPE_NAME   => 12,
        MINIMUM_SCALE     => 13,
        MAXIMUM_SCALE     => 14,
        SQL_DATA_TYPE     => 15,
        SQL_DATETIME_SUB  => 16,
        NUM_PREC_RADIX    => 17,
        INTERVAL_PRECISION=> 18,
    },
    [ 'VARCHAR', SQL_VARCHAR,
        undef, "'","'", undef,0, 1,1,0,0,0,undef,1,255, undef
    ],
    [ 'INTEGER', SQL_INTEGER,
        undef,  "", "", undef,0, 0,1,0,0,0,undef,0,  0, 10
    ],
  ];

More than one row may have the same value in the DATA_TYPE field if there are different ways to spell the type name and/or there are variants of the type with different attributes (e.g., with and without AUTO_UNIQUE_VALUE set, with and without UNSIGNED_ATTRIBUTE, etc).

その型の名前に違った書き方があったり、属性の違いで型のバリエーションが あったり(例えば AUTO_UNIQUE_VALUE があったりなかったり、 UNSIGNED_ATTRIBUTE があったりなかったりなど)すれば、一つ以上のフィールドが DATA_TYPE フィールドに同じ値をもつこともあることに注意してください。

The rows are ordered by DATA_TYPE first and then by how closely each type maps to the corresponding ODBC SQL data type, closest first.

行はまず DATA_TYPE で順に、そして ODBC SQL データ型にどれくらい近く 対応しているかによって近いほど先に順に並びます。

The meaning of the fields is described in the documentation for the "type_info" method.

各フィールドの意味は "type_info" メソッドで説明しています。

An 'index' hash is provided so you don't need to rely on index values defined above. However, using DBD::ODBC with some old ODBC drivers may return older names, shown as comments in the example above. Another issue with the index hash is that the lettercase of the keys is not defined. It is usually uppercase, as show here, but drivers may return names with any lettercase.

'index' ハッシュが提供されるので、上で定義されているインデックス値に 頼る必要はありません。 しかし、古い ODBC ドライバで DBD::ODBC を使うと、上述の例のコメントに あるように、古い名前を返すかもしれません。 インデックスハッシュに関するもう一つの問題は、キーの大文字小文字が 未定義であることです。 それは通常、ここで見てきたように大文字ですが、ドライバは名前を大文字、 小文字のどちらで返しても自由です。

Drivers are also free to return extra driver-specific columns of information - though it's recommended that they start at column index 50 to leave room for expansion of the DBI/ODBC specification.

ドライバは特別なドライバ専用の情報のカラムを返すのも自由です - しかし DBI/ODBC 仕様の拡張のための空間をあけておくためにカラムインデックス 50 から 始めることをお勧めします。

The type_info_all() method is not normally used directly. The "type_info" method provides a more usable and useful interface to the data.

The type_info_all() method is not normally used directly. The "type_info" method provides a more usable and useful interface to the data. (TBT)

type_info

  @type_info = $dbh->type_info($data_type);

Returns a list of hash references holding information about one or more variants of $data_type. The list is ordered by DATA_TYPE first and then by how closely each type maps to the corresponding ODBC SQL data type, closest first. If called in a scalar context then only the first (best) element is returned.

一つあるいは複数の $data_type の変形についての情報が入ったハッシュへの リファレンスのリストが返されます。 リストはまず DATA_TYPE によって並べられ、そして各型が ODBC SQL データ型に どらくらい近く対応しているかによって近いほど先に順に並びます。 スカラコンテキストで呼ばれれば、最初の(もっともよい)要素だけが返されます。

If $data_type is undefined or SQL_ALL_TYPES, then the list will contain hashes for all data type variants supported by the database and driver.

$data_type が未定義か SQL_ALL_TYPES であれば、リストにはデータベースと ドライバによってサポートされているすべてのデータ型が入ります。

If $data_type is an array reference then type_info returns the information for the first type in the array that has any matches.

もし $data_type が配列リファレンスであれば、type_info はその配列の いずれかが対応する最初の型のための情報を返します。

The keys of the hash follow the same letter case conventions as the rest of the DBI (see "Naming Conventions and Name Space"). The following uppercase items should always exist, though may be undef:

以下のハッシュのキーは DBI の他の部分と同じようにすべて大文字もしくは 小文字で表わされます。 ("Naming Conventions and Name Space" をご覧ください)。 以下に示す大文字要素は間違い無く存在しますが、未定義かもしれません:

TYPE_NAME (string)

Data type name for use in CREATE TABLE statements etc.

CREATE TABLE 文などで使われるデータ型名。

DATA_TYPE (integer)

SQL data type number.

SQL データ型番号。

COLUMN_SIZE (integer)

For numeric types, this is either the total number of digits (if the NUM_PREC_RADIX value is 10) or the total number of bits allowed in the column (if NUM_PREC_RADIX is 2).

数値型については、これは(NUM_PREC_RADIX の値が 10 であれば)総桁数、 もしくは(NUM_PREC_RADIX の値が 2 であれば)カラムの中に許されるビットの 総数。

For string types, this is the maximum size of the string in characters.

文字列型であれば、これは文字列の最大サイズを文字数で表したもの。

For date and interval types, this is the maximum number of characters needed to display the value.

日付(date)および期間(interval)型であれば、その値を表示するために必要な文字の 最大数です。

LITERAL_PREFIX (string)

Characters used to prefix a literal. A typical prefix is "'" for characters, or possibly "0x" for binary values passed as hexadecimal. NULL (undef) is returned for data types for which this is not applicable.

リテラルの最初に使われる文字。 典型的なものとしては文字型には "'"、バイナリ値には 16 進数を表わす "0x"。 このデータ型に当てはまらなければ、NULL (undef) が返されます。

LITERAL_SUFFIX (string)

Characters used to suffix a literal. Typically "'" for characters. NULL (undef) is returned for data types where this is not applicable.

リテラルの最後に使われる文字。 典型的なものとしては文字型には "'"。 このデータ型に当てはまらなければ、NULL (undef)。

CREATE_PARAMS (string)

Parameter names for data type definition. For example, CREATE_PARAMS for a DECIMAL would be "precision,scale" if the DECIMAL type should be declared as DECIMAL(precision,scale) where precision and scale are integer values. For a VARCHAR it would be "max length". NULL (undef) is returned for data types for which this is not applicable.

データ型定義のためのパラメータ名。 例えば DECIMALDECIMAL(precision,scale) (全体桁数,小数点以下桁数)、 precisionscale は整数値のように宣言されなければならないのであれば、 DECIMAL のための CREATE_PARAMS は "precision,scale" になります。 VARCHAR では "max length"(最大長)になります。 このデータ型に当てはまらなければ、NULL (undef) が返されます。

NULLABLE (integer)

Indicates whether the data type accepts a NULL value: 0 or an empty string = no, 1 = yes, 2 = unknown.

このデータ型がNULL値を受け入れるかどうかを示します: ( 0 または空文字列 = 受け入れない, 1 = 受け入れる, 2 = 不明)

CASE_SENSITIVE (boolean)

Indicates whether the data type is case sensitive in collations and comparisons.

このデータ型が照会や比較のさいに大文字、小文字を区別するかどうかを示します。

SEARCHABLE (integer)

Indicates how the data type can be used in a WHERE clause, as follows:

データタイプが WHERE 句で以下のように使用できるかどうかを示します:

  0 - Cannot be used in a WHERE clause
  1 - Only with a LIKE predicate
  2 - All comparison operators except LIKE
  3 - Can be used in a WHERE clause with any comparison operator
  0 - WHERE 句で使うことはできません
  1 - LIKE と一緒になら使えます。
  2 - LIKE を除いてすべての比較演算子が使えます
  3 - WHERE 句においてすべての比較演算子が使えます
UNSIGNED_ATTRIBUTE (boolean)

Indicates whether the data type is unsigned. NULL (undef) is returned for data types for which this is not applicable.

データ型が符号なしであるかどうかを示します。 このデータ型に当てはまらなければ、NULL (undef) が返されます。

FIXED_PREC_SCALE (boolean)

Indicates whether the data type always has the same precision and scale (such as a money type). NULL (undef) is returned for data types for which this is not applicable.

そのデータ型が(money 型のように)常に同じ精度、桁数を持つかどうかを 示します。 このデータ型に当てはまらなければ、NULL (undef) が返されます。

AUTO_UNIQUE_VALUE (boolean)

Indicates whether a column of this data type is automatically set to a unique value whenever a new row is inserted. NULL (undef) is returned for data types for which this is not applicable.

新しい行が挿入するときにはいつも、このデータ型のカラムは自動的に ユニークな値に設定されるかどうかを示します。 このデータ型に当てはまらなければ、NULL (undef) が返されます。

LOCAL_TYPE_NAME (string)

Localized version of the TYPE_NAME for use in dialog with users. NULL (undef) is returned if a localized name is not available (in which case TYPE_NAME should be used).

ユーザとの対話に使われる TYPE_NAME のローカル化されたバージョン。 ローカル化された名前がなければNULL (undef)(この場合は TYPE_NAME を 使わなければなりません)。

MINIMUM_SCALE (integer)

The minimum scale of the data type. If a data type has a fixed scale, then MAXIMUM_SCALE holds the same value. NULL (undef) is returned for data types for which this is not applicable.

データ型の最小桁数。 データ型が決まった桁数をもっていれば、MAXIMUM_SCALE と同じになります。 このデータ型に当てはまらなければ、NULL (undef) が返されます。

MAXIMUM_SCALE (integer)

The maximum scale of the data type. If a data type has a fixed scale, then MINIMUM_SCALE holds the same value. NULL (undef) is returned for data types for which this is not applicable.

データ型の最大桁数。 データ型が決まった桁数をもっていれば、MINIMUM_SCALE と同じになります。 このデータ型に当てはまらなければ、NULL (undef) が返されます。

SQL_DATA_TYPE (integer)

This column is the same as the DATA_TYPE column, except for interval and datetime data types. For interval and datetime data types, the SQL_DATA_TYPE field will return SQL_INTERVAL or SQL_DATETIME, and the SQL_DATETIME_SUB field below will return the subcode for the specific interval or datetime data type. If this field is NULL, then the driver does not support or report on interval or datetime subtypes.

期間(interval)と日時(datetime)型を除いては、このカラムは DATA_TYPE と 同じです。 期間(interval)と日時(datetime)型であれば、SQL_DATA_TYPESQL_INTERVAL もしくは SQL_DATETIME を返し、以下の SQL_DATETIME_SUB は 特定の期間(interval)または日時(datetime)型のためのサブコードを返します。 もしこのフィールドが NULL であれば、ドライバは期間(interval)または 日時(datetime)型をサポートしていないか、報告しません。

SQL_DATETIME_SUB (integer)

For interval or datetime data types, where the SQL_DATA_TYPE field above is SQL_INTERVAL or SQL_DATETIME, this field will hold the subcode for the specific interval or datetime data type. Otherwise it will be NULL (undef).

期間(interval)と日時(datetime)型であれば、上記の SQL_DATA_TYPESQL_INTERVAL もしくは SQL_DATETIME を返し、 このフィールドは特定の期間(interval)または日時(datetime)型のための サブコードを返します。 そうでなければNULL(undef)になります。

Although not mentioned explicitly in the standards, it seems there is a simple relationship between these values:

標準には明示的に記述されていませんが、これらの値には単純な関係が あるようです:

  DATA_TYPE == (10 * SQL_DATA_TYPE) + SQL_DATETIME_SUB
NUM_PREC_RADIX (integer)

The radix value of the data type. For approximate numeric types, NUM_PREC_RADIX contains the value 2 and COLUMN_SIZE holds the number of bits. For exact numeric types, NUM_PREC_RADIX contains the value 10 and COLUMN_SIZE holds the number of decimal digits. NULL (undef) is returned either for data types for which this is not applicable or if the driver cannot report this information.

そのデータ型の基数を返します。 概算の数値型では、NUM_PREC_RADIX の値は 2 で COLUMN_SIZE はビットの数を 持ちます。 厳密な数値型では NUM_PREC_RADIX の値は 10 で、COLUMN_SIZE には 10 進数の桁数が入ります。 このデータ型に当てはまらないか、ドライバがこの情報を報告できなければ、 NULL (undef) が返されます。

INTERVAL_PRECISION (integer)

The interval leading precision for interval types. NULL is returned either for data types for which this is not applicable or if the driver cannot report this information.

期間(interval)型のための先行精度です。 このデータ型に当てはまらないか、ドライバがこの情報を報告できなければ、 NULL (undef) が返されます。

For example, to find the type name for the fields in a select statement you can do:

例えば select 文でのフィールドのためのデータ型名を見つけるには 以下のようにすることができます:

  @names = map { scalar $dbh->type_info($_)->{TYPE_NAME} } @{ $sth->{TYPE} }

Since DBI and ODBC drivers vary in how they map their types into the ISO standard types you may need to search for more than one type. Here's an example looking for a usable type to store a date:

DBI と ODBC ドライバとは型を ISO 標準型にどのようにマッピングするのかが 異なっているため、一つ以上の型を探さなければならないかもしれません。 以下に日付を格納するのに使えるデータ型を探す例を示します:

  $my_date_type = $dbh->type_info( [ SQL_DATE, SQL_TIMESTAMP ] );

Similarly, to more reliably find a type to store small integers, you could use a list starting with SQL_SMALLINT, SQL_INTEGER, SQL_DECIMAL, etc.

同じように、小さな整数を格納するための型の検索を信頼できるようにするため、 SQL_SMALLINT, SQL_INTEGER, SQL_DECIMAL などから始まるリストを 使うこともできます。

"Standards Reference Information" も参照してください。

quote

  $sql = $dbh->quote($value);
  $sql = $dbh->quote($value, $data_type);

Quote a string literal for use as a literal value in an SQL statement, by escaping any special characters (such as quotation marks) contained within the string and adding the required type of outer quotation marks.

文字列の中の(クォーテーションマークのような)特殊な文字をエスケープし、 必要とされるタイプの外側のクォーテーションマークを加えることにより、 文字列リテラルを SQL 文で使うリテラル値として使えるようにクォートします。

  $sql = sprintf "SELECT foo FROM bar WHERE baz = %s",
                $dbh->quote("Don't");

For most database types, at least those that conform to SQL standards, quote would return 'Don''t' (including the outer quotation marks). For others it may return something like 'Don\'t'

ほとんどのデータベースでは、少なくとも SQL 標準に従っているものなら、 quote は 'Don"t' を返します(外側のクォーテーションマークを含みます)。 その他の場合は 'Don\'t' のようなものを返します。

An undefined $value value will be returned as the string NULL (without single quotation marks) to match how NULLs are represented in SQL.

未定義の $value の値は SQL で NULL を表すことに対応するよう、文字列 NULL (シングルクォーテションマークなし)になります。

If $data_type is supplied, it is used to try to determine the required quoting behaviour by using the information returned by "type_info". As a special case, the standard numeric types are optimized to return $value without calling type_info.

$data_type が与えられると、"type_info" から返される情報を元にして 要求されたクォートの処理を決めます。 特殊な場合として、標準の数値型は type_info を呼ばずに、$value を 返すように最適化されています。

Quote will probably not be able to deal with all possible input (such as binary data or data containing newlines), and is not related in any way with escaping or quoting shell meta-characters.

quote は(バイナリデータや改行が入っているデータのように)すべての入力に 対応できるわけではありません; そしてシェルのエスケープやメタ文字にはまったく 関連してはいません。

It is valid for the quote() method to return an SQL expression that evaluates to the desired string. For example:

必要な文字列を評価する SQL 式を返すための quote() メソッドも有効です。 例えば:

  $quoted = $dbh->quote("one\ntwo\0three")

may return something like:

というものは以下のようなものを返します:

  CONCAT('one', CHAR(12), 'two', CHAR(0), 'three')

The quote() method should not be used with "Placeholders and Bind Values".

quote() メソッドは "Placeholders and Bind Values" と使うべきでは ありません

quote_identifier

  $sql = $dbh->quote_identifier( $name );
  $sql = $dbh->quote_identifier( $catalog, $schema, $table, \%attr );

Quote an identifier (table name etc.) for use in an SQL statement, by escaping any special characters (such as double quotation marks) it contains and adding the required type of outer quotation marks.

Quote an identifier (table name etc.) for use in an SQL statement, by escaping any special characters (such as double quotation marks) it contains and adding the required type of outer quotation marks. (TBT)

Undefined names are ignored and the remainder are quoted and then joined together, typically with a dot (.) character. For example:

未定義の名前は無視され、残りはクォートされてから互いに (典型的にはドット (.) 文字で)結合されます。 例えば:

  $id = $dbh->quote_identifier( undef, 'Her schema', 'My table' );

would, for most database types, return "Her schema"."My table" (including all the double quotation marks).

というのは、ほとんどのデータベース型では、 "Her schema"."My table" (ダブルクォートを含みます) を返します。

If three names are supplied then the first is assumed to be a catalog name and special rules may be applied based on what "get_info" returns for SQL_CATALOG_NAME_SEPARATOR (41) and SQL_CATALOG_LOCATION (114). For example, for Oracle:

If three names are supplied then the first is assumed to be a catalog name and special rules may be applied based on what "get_info" returns for SQL_CATALOG_NAME_SEPARATOR (41) and SQL_CATALOG_LOCATION (114). For example, for Oracle: (TBT)

  $id = $dbh->quote_identifier( 'link', 'schema', 'table' );

would return "schema"."table"@"link".

"schema"."table"@"link" を返します。

take_imp_data

  $imp_data = $dbh->take_imp_data;

Leaves the $dbh in an almost dead, zombie-like, state and returns a binary string of raw implementation data from the driver which describes the current database connection. Effectively it detaches the underlying database API connection data from the DBI handle. After calling take_imp_data(), all other methods except DESTROY will generate a warning and return undef.

Leaves the $dbh in an almost dead, zombie-like, state and returns a binary string of raw implementation data from the driver which describes the current database connection. Effectively it detaches the underlying database API connection data from the DBI handle. After calling take_imp_data(), all other methods except DESTROY will generate a warning and return undef. (TBT)

Why would you want to do this? You don't, forget I even mentioned it. Unless, that is, you're implementing something advanced like a multi-threaded connection pool. See DBI::Pool.

Why would you want to do this? You don't, forget I even mentioned it. Unless, that is, you're implementing something advanced like a multi-threaded connection pool. See DBI::Pool. (TBT)

The returned $imp_data can be passed as a dbi_imp_data attribute to a later connect() call, even in a separate thread in the same process, where the driver can use it to 'adopt' the existing connection that the implementation data was taken from.

The returned $imp_data can be passed as a dbi_imp_data attribute to a later connect() call, even in a separate thread in the same process, where the driver can use it to 'adopt' the existing connection that the implementation data was taken from. (TBT)

Some things to keep in mind...

覚えておくべきことは…

* the $imp_data holds the only reference to the underlying database API connection data. That connection is still 'live' and won't be cleaned up properly unless the $imp_data is used to create a new $dbh which is then allowed to disconnect() normally.

* the $imp_data holds the only reference to the underlying database API connection data. That connection is still 'live' and won't be cleaned up properly unless the $imp_data is used to create a new $dbh which is then allowed to disconnect() normally. (TBT)

* using the same $imp_data to create more than one other new $dbh at a time may well lead to unpleasant problems. Don't do that.

* using the same $imp_data to create more than one other new $dbh at a time may well lead to unpleasant problems. Don't do that. (TBT)

Any child statement handles are effectively destroyed when take_imp_data() is called.

子文ハンドルは、take_imp_data() が呼び出されると正しく破壊されます。

The take_imp_data method was added in DBI 1.36 but wasn't useful till 1.49.

take_imp_data メソッドは DBI 1.36 で追加されましたが 1.49 までは有用ではありませんでした。

データベースハンドル属性

This section describes attributes specific to database handles.

このセクションではデータベースハンドルに特有の属性について記述します。

Changes to these database handle attributes do not affect any other existing or future database handles.

これらのデータベースハンドル属性を変更しても、既存の他の データベースハンドルあるいはこの後、生成されるデータベースハンドルには 影響を与えません。

Attempting to set or get the value of an unknown attribute generates a warning, except for private driver-specific attributes (which all have names starting with a lowercase letter).

ドライバ毎のプライベートな属性(属性は名前が小文字ではじまります)を 除いては、決められていない属性を設定あるいは取得しようとすると 警告が発生します。

Example:

例:

  $h->{AutoCommit} = ...;       # set/write
  ... = $h->{AutoCommit};       # get/read

AutoCommit (boolean)

If true, then database changes cannot be rolled-back (undone). If false, then database changes automatically occur within a "transaction", which must either be committed or rolled back using the commit or rollback methods.

真であれば、データベースの変更をロールバックする(元に戻す)ことは できません。 偽であれば、データベースの変更は自動的に「トランザクション」の中に入り、 commit または rollback メソッドを使ってコミットあるいは ロールバックされなければなりません。

Drivers should always default to AutoCommit mode (an unfortunate choice largely forced on the DBI by ODBC and JDBC conventions.)

ドライバはデフォルトを AutoCommit モードにしなければいけません (ODBC と JDBC の決まりにより、残念ながら DBI はこうせざるを得ません。)

Attempting to set AutoCommit to an unsupported value is a fatal error. This is an important feature of the DBI. Applications that need full transaction behaviour can set $dbh->{AutoCommit} = 0 (or set AutoCommit to 0 via "connect") without having to check that the value was assigned successfully.

AutoCommit をサポートされていない値に設定しようとすると、致命的な エラーになります。 これは DBI の重要な機能です。 完全なトランザクションを必要とするアプリケーションは、値が正しく代入されたか どうかをチェックすることなく $dbh->{AutoCommit} = 0 と する(または "connect" メソッドでの AutoCommit を 0 に設定する)ことが できます。

For the purposes of this description, we can divide databases into three categories:

この点から、データベースを三つのカテゴリに分けることができます。

  Databases which don't support transactions at all.
  Databases in which a transaction is always active.
  Databases in which a transaction must be explicitly started ('BEGIN WORK').
  全くトランザクションをサポートしていないデータベース
  いつでもトランザクションが有効なデータベース
  明示的にトランザクションを開始('BEGIN WORK'などにより)しなければいけないデータベース

* Databases which don't support transactions at all

* 全くトランザクションをサポートしていないデータベース

For these databases, attempting to turn AutoCommit off is a fatal error. commit and rollback both issue warnings about being ineffective while AutoCommit is in effect.

これらのデータベースで、AutoCommit をオフにしようとすると 致命的エラーになります。 commit, rollbackAutoCommit が有効な間は無効であるという 警告を起こします。

* Databases in which a transaction is always active

* いつでもトランザクションが有効なデータベース

These are typically mainstream commercial relational databases with "ANSI standard" transaction behaviour. If AutoCommit is off, then changes to the database won't have any lasting effect unless "commit" is called (but see also "disconnect"). If "rollback" is called then any changes since the last commit are undone.

「ANSI標準」トランザクション機能を持った商用リレーショナルデータベースでは、 これが主流です。 AutoCommit がオフであると、データベースへの変更は "commit" されるまで 有効になりません (しかし "disconnect" もご覧ください)。 もし "rollback" が呼ばれると、最後のコミット以降のいかなる変更も元に 戻されます。

If AutoCommit is on, then the effect is the same as if the DBI called commit automatically after every successful database operation. So calling commit or rollback explicitly while AutoCommit is on would be ineffective because the changes would have already been committed.

AutoCommit がオンであると、DBI はまるで正常終了したデータベース操作の後、 自動的に commit を呼んでいるのと同じように振る舞います。 従って AutoCommit がオンの間に commit, rollback を明示的に 呼び出しても、すでにコミットされてしまっているので、何も効果がありません。

Changing AutoCommit from off to on will trigger a "commit".

AutoCommit をオフからオンに変えると、大抵のドライバは "commit" します。

For databases which don't support a specific auto-commit mode, the driver has to commit each statement automatically using an explicit COMMIT after it completes successfully (and roll it back using an explicit ROLLBACK if it fails). The error information reported to the application will correspond to the statement which was executed, unless it succeeded and the commit or rollback failed.

自動コミットモードを特にサポートしていないデータベースでは、ドライバは 各文が正常終了したら、明示的に COMMIT することにより、 自動的にコミットしなければいけません(失敗したら明示的に ROLLBACK して 元に戻さなければいけません)。 アプリケーションに伝えられるエラー情報は、文が正常終了した後、 コミットやロールバックが失敗しない限りは、実行された文に 対応しなければいけません。

* Databases in which a transaction must be explicitly started

* トランザクションが明示的に開始されなければならないデータベース

For these databases, the intention is to have them act like databases in which a transaction is always active (as described above).

これらのデータベースでは、トランザクションは(上記のような)いつでも 有効になるデータベースと同じようにします。

To do this, the driver will automatically begin an explicit transaction when AutoCommit is turned off, or after a "commit" or "rollback" (or when the application issues the next database operation after one of those events).

こうするため、ドライバは AutoCommit がオフになるか、 "commit""rollback" の後(あるいはアプリケーションがこれらの イベントの一つの後次のデータベース操作を行ったとき)、自動的に トランザクションを開始します。

In this way, the application does not have to treat these databases as a special case.

こうして、アプリケーションはこれらのデータベースを特別なケースとして 扱わなくてもよくなるのです。

See "commit", "disconnect" and "Transactions" for other important notes about transactions.

トランザクションについてのほかの重要な情報については "commit", "disconnect", "Transactions" をご覧ください。

Driver (handle)

Holds the handle of the parent driver. The only recommended use for this is to find the name of the driver using:

ハンドルの親ドライバを保持します。 唯一推奨されるこれの使い方は以下のようにしてドライバの名前を 見つけることだけです:

  $dbh->{Driver}->{Name}

Name (string)

Holds the "name" of the database. Usually (and recommended to be) the same as the "dbi:DriverName:..." string used to connect to the database, but with the leading "dbi:DriverName:" removed.

データベースの名前が入ります。 通常は(そして推奨されることですが)データベースへの接続に使われる "dbi:DriverName:..." 文字列から先頭の "dbi:DriverName:" を 取ったものになります。

Statement (string, read-only)

Returns the statement string passed to the most recent "prepare" method called in this database handle, even if that method failed. This is especially useful where RaiseError is enabled and the exception handler checks $@ and sees that a 'prepare' method call failed.

このデータベースハンドルで最後の "prepare" メソッドに渡された 文文字列を返します。 もしそのメソッドが失敗していたとしてもです。 これは RaiseError が有効になっていて、例外ハンドラが $@ をチェックし、 'prepare' メソッドが失敗したかもしれないと思われるときには特に便利でしょう。

RowCacheSize (integer)

A hint to the driver indicating the size of the local row cache that the application would like the driver to use for future SELECT statements. If a row cache is not implemented, then setting RowCacheSize is ignored and getting the value returns undef.

アプリケーションがドライバに後からの SELECT 文のために使わせたい ローカルな行キャッシュの大きさを示すドライバへのヒントです。 行キャッシュが実装されていなければ、RowCacheSize の設定は無視され、値は undef が返ります。

Some RowCacheSize values have special meaning, as follows:

RowCacheSize の値には以下のような意味があります:

  0 - Automatically determine a reasonable cache size for each SELECT
  1 - Disable the local row cache
 >1 - Cache this many rows
 <0 - Cache as many rows that will fit into this much memory for each SELECT.
  0 - 自動的に各 SELECT に適切なキャッシュサイズを決めます
  1 - ローカル行キャッシュを使用しません
 >1 - この数だけ行をキャッシュします
 <0 - 各 SELECT のためにメモリの量に合わせてできるだけ多くの行をキャッシュします

Note that large cache sizes may require a very large amount of memory (cached rows * maximum size of row). Also, a large cache will cause a longer delay not only for the first fetch, but also whenever the cache needs refilling.

キャッシュの大きさを大きくすると大量のメモリが必要になること (キャッシュされる行の数×行の最大サイズ)、そして大きなキャッシュをとると それだけ最初の取得あるいは次のキャッシュ分を取得のさいに時間がかかるように なることに注意してください。

See also the "RowsInCache" statement handle attribute.

"RowsInCache" 文ハンドル属性もご覧ください。

Username (string)

Returns the username used to connect to the database.

データベースとの接続に使われたユーザー名を返します。

DBI 文ハンドルオブジェクト

This section lists the methods and attributes associated with DBI statement handles.

この節では DBI 文ハンドルに関連するメソッドと属性を一覧にします。

文ハンドルメソッド

The DBI defines the following methods for use on DBI statement handles:

DBI は DBI 文ハンドルのために以下のメソッドを定義しています:

bind_param

  $sth->bind_param($p_num, $bind_value)
  $sth->bind_param($p_num, $bind_value, \%attr)
  $sth->bind_param($p_num, $bind_value, $bind_type)

The bind_param method takes a copy of $bind_value and associates it (binds it) with a placeholder, identified by $p_num, embedded in the prepared statement. Placeholders are indicated with question mark character (?). For example:

bind_param メソッドは $bind_value のコピーを取って、prepared 文に 埋め込まれている、$p_num で識別されるプレースホルダと結びつけます。 プレースホルダは疑問符(?)により示されます。 例えば:

  $dbh->{RaiseError} = 1;        # save having to check each method call
  $sth = $dbh->prepare("SELECT name, age FROM people WHERE name LIKE ?");
  $sth->bind_param(1, "John%");  # placeholders are numbered from 1
  $sth->execute;
  DBI::dump_results($sth);
  $dbh->{RaiseError} = 1;        # 各メソッド呼び出しをチェックするようにする
  $sth = $dbh->prepare("select name, age from people where name like ?");
  $sth->bind_param(1, "John%");  # プレースホルダは 1 から順番
  $sth->execute;
  DBI::dump_results($sth);

See "Placeholders and Bind Values" for more information.

さらなる情報については "Placeholders and Bind Values" を 参照してください。

Data Types for Placeholders

プレースホルダのデータ型

The \%attr parameter can be used to hint at the data type the placeholder should have. This is rarely needed. Typically, the driver is only interested in knowing if the placeholder should be bound as a number or a string.

\%attr パラメータはプレースホルダが持つべきデータ型を指定するために 使われます。 通常、ドライバはプレースホルダが結びつけられるのが数値としてなのか、 文字列としてなのかを知ることだけに関心があります。

  $sth->bind_param(1, $value, { TYPE => SQL_INTEGER });

As a short-cut for the common case, the data type can be passed directly, in place of the \%attr hash reference. This example is equivalent to the one above:

よくあるケースのための短縮形として、データ型を直接 \%attr ハッシュリファレンスの場所に直接、渡すことができます。 この例は、上記のものと同じです。

  $sth->bind_param(1, $value, SQL_INTEGER);

The TYPE value indicates the standard (non-driver-specific) type for this parameter. To specify the driver-specific type, the driver may support a driver-specific attribute, such as { ora_type => 97 }.

TYPE の値はこのパラメータでは(ドライバに特有でない)標準の型を示します。 ドライバ特有の型を指定するために、ドライバは { ora_type = 97 }> といった ドライバ特有の型をサポートしていることがあります。

The SQL_INTEGER and other related constants can be imported using

SQL_INTEGER および関連する定数は以下のようにしてインポートできます

  use DBI qw(:sql_types);

See "DBI Constants" for more information.

さらなる情報については "DBI Constants" を参照してください。

The data type is 'sticky' in that bind values passed to execute() are bound with the data type specified by earlier bind_param() calls, if any. Portable applications should not rely on being able to change the data type after the first bind_param call.

The data type is 'sticky' in that bind values passed to execute() are bound with the data type specified by earlier bind_param() calls, if any. Portable applications should not rely on being able to change the data type after the first bind_param call. (TBT)

Perl only has string and number scalar data types. All database types that aren't numbers are bound as strings and must be in a format the database will understand except where the bind_param() TYPE attribute specifies a type that implies a particular format. For example, given:

Perl は文字と数値のスカラデータ型だけを持っています。 数値でないすべてのデータベース型は文字列に結び付けられ、データベースが 理解できる形式に変換されなければなりません。 except where the bind_param() TYPE attribute specifies a type that implies a particular format. 例えば、以下のものは: (TBT)

  $sth->bind_param(1, $value, SQL_DATETIME);

the driver should expect $value to be in the ODBC standard SQL_DATETIME format, which is 'YYYY-MM-DD HH:MM:SS'. Similarly for SQL_DATE, SQL_TIME etc.

the driver should expect $value to be in the ODBC standard SQL_DATETIME format, which is 'YYYY-MM-DD HH:MM:SS'. Similarly for SQL_DATE, SQL_TIME etc. (TBT)

As an alternative to specifying the data type in the bind_param call, you can let the driver pass the value as the default type (VARCHAR). You can then use an SQL function to convert the type within the statement. For example:

データ型を bind_param 呼び出しの際に指定する代わりに、ドライバに データをデフォルトの型(VARCHAR)として渡すこともできます。 そして SQL 関数で文の中で変換することができます。 例えば:

  INSERT INTO price(code, price) VALUES (?, CONVERT(MONEY,?))

The CONVERT function used here is just an example. The actual function and syntax will vary between different databases and is non-portable.

CONVERT 関数は単なる例として使われています。 実際の関数と書き方はデータベースによって大きく違いますし、移植性もありません。

See also "Placeholders and Bind Values" for more information.

詳しい情報については "Placeholders and Bind Values" もご覧下さい。

bind_param_inout

  $rc = $sth->bind_param_inout($p_num, \$bind_value, $max_len)  or die $sth->errstr;
  $rv = $sth->bind_param_inout($p_num, \$bind_value, $max_len, \%attr)     or ...
  $rv = $sth->bind_param_inout($p_num, \$bind_value, $max_len, $bind_type) or ...

This method acts like "bind_param", but also enables values to be updated by the statement. The statement is typically a call to a stored procedure. The $bind_value must be passed as a reference to the actual value to be used.

このメソッドは "bind_param" と似ていますが、文からの更新も 可能としています。 文は通常、ストアドプロシージャと呼ばれます。 $bind_value は実際に使われる変数へのリファレンスとして渡されます。

Note that unlike "bind_param", the $bind_value variable is not copied when bind_param_inout is called. Instead, the value in the variable is read at the time "execute" is called.

"bind_param" とは違い、$bind_value 変数は bind_param_inout が 呼ばれたときにはコピーされないことに注意してください。 変数の値は "execute" が呼ばれたときに読みこまれます。

The additional $max_len parameter specifies the minimum amount of memory to allocate to $bind_value for the new value. If the value returned from the database is too big to fit, then the execution should fail. If unsure what value to use, pick a generous length, i.e., a length larger than the longest value that would ever be returned. The only cost of using a larger value than needed is wasted memory.

追加された $max_len パラメータは、$bin_value の新しい値のために 確保される最小限のメモリ量を指定します。 もし実際の値が大きすぎて収まらなければ、実行は失敗します。 使用する量がわからなければ、大きな長さを惜しみなく、つまり 返されるかもしれない一番長い値より長く値を指定しましょう。 必要よりも大きな値を使うために犠牲になるのは、メモリの浪費だけです。

Undefined values or undef are used to indicate null values. See also "Placeholders and Bind Values" for more information.

未定義の値あるいは undef は NULL 値を示すのに使われます。 さらに詳しい情報は "Placeholders and Bind Values" もご覧下さい。

bind_param_array

  $rc = $sth->bind_param_array($p_num, $array_ref_or_value)
  $rc = $sth->bind_param_array($p_num, $array_ref_or_value, \%attr)
  $rc = $sth->bind_param_array($p_num, $array_ref_or_value, $bind_type)

The bind_param_array method is used to bind an array of values to a placeholder embedded in the prepared statement which is to be executed with "execute_array". For example:

The bind_param_array method is used to bind an array of values to a placeholder embedded in the prepared statement which is to be executed with "execute_array". For example: (TBT)

  $dbh->{RaiseError} = 1;        # save having to check each method call
  $sth = $dbh->prepare("INSERT INTO staff (first_name, last_name, dept) VALUES(?, ?, ?)");
  $sth->bind_param_array(1, [ 'John', 'Mary', 'Tim' ]);
  $sth->bind_param_array(2, [ 'Booth', 'Todd', 'Robinson' ]);
  $sth->bind_param_array(3, "SALES"); # scalar will be reused for each row
  $sth->execute_array( { ArrayTupleStatus => \my @tuple_status } );

The %attr ($bind_type) argument is the same as defined for "bind_param". Refer to "bind_param" for general details on using placeholders.

The %attr ($bind_type) argument is the same as defined for "bind_param". Refer to "bind_param" for general details on using placeholders. (TBT)

(Note that bind_param_array() can not be used to expand a placeholder into a list of values for a statement like "SELECT foo WHERE bar IN (?)". A placeholder can only ever represent one value per execution.)

(Note that bind_param_array() can not be used to expand a placeholder into a list of values for a statement like "SELECT foo WHERE bar IN (?)". A placeholder can only ever represent one value per execution.) (TBT)

Scalar values, including undef, may also be bound by bind_param_array. In which case the same value will be used for each "execute" call. Driver-specific implementations may behave differently, e.g., when binding to a stored procedure call, some databases may permit mixing scalars and arrays as arguments.

Scalar values, including undef, may also be bound by bind_param_array. In which case the same value will be used for each "execute" call. Driver-specific implementations may behave differently, e.g., when binding to a stored procedure call, some databases may permit mixing scalars and arrays as arguments. (TBT)

The default implementation provided by DBI (for drivers that have not implemented array binding) is to iteratively call "execute" for each parameter tuple provided in the bound arrays. Drivers may provide more optimized implementations using whatever bulk operation support the database API provides. The default driver behaviour should match the default DBI behaviour, but always consult your driver documentation as there may be driver specific issues to consider.

The default implementation provided by DBI (for drivers that have not implemented array binding) is to iteratively call "execute" for each parameter tuple provided in the bound arrays. Drivers may provide more optimized implementations using whatever bulk operation support the database API provides. The default driver behaviour should match the default DBI behaviour, but always consult your driver documentation as there may be driver specific issues to consider. (TBT)

Note that the default implementation currently only supports non-data returning statements (INSERT, UPDATE, but not SELECT). Also, bind_param_array and "bind_param" cannot be mixed in the same statement execution, and bind_param_array must be used with "execute_array"; using bind_param_array will have no effect for "execute".

Note that the default implementation currently only supports non-data returning statements (INSERT, UPDATE, but not SELECT). Also, bind_param_array and "bind_param" cannot be mixed in the same statement execution, and bind_param_array must be used with "execute_array"; using bind_param_array will have no effect for "execute". (TBT)

The bind_param_array method was added in DBI 1.22.

bind_param_array メソッドは DBI 1.22 で追加されました。

execute

  $rv = $sth->execute                or die $sth->errstr;
  $rv = $sth->execute(@bind_values)  or die $sth->errstr;

Perform whatever processing is necessary to execute the prepared statement. An undef is returned if an error occurs. A successful execute always returns true regardless of the number of rows affected, even if it's zero (see below). It is always important to check the return status of execute (and most other DBI methods) for errors if you're not using "RaiseError".

prepare された文を実行するために必要な処理をすべて行います。 エラーが発生したら、undef が返されます。 正常な execute は、影響を受けた行の数に関係無く、例えそれが 0 であっても(下記を参照)真を返します。 "RaiseError" を使っていないなら、execute(そして他のほとんどの DBI メソッド)の戻りステータスをエラーでないかチェックすることは 常に重要です。

For a non-SELECT statement, execute returns the number of rows affected, if known. If no rows were affected, then execute returns "0E0", which Perl will treat as 0 but will regard as true. Note that it is not an error for no rows to be affected by a statement. If the number of rows affected is not known, then execute returns -1.

SELECT 文なら、execute は、もしわかれば影響を受けた行の数を 返します。 影響を受けた行が無い場合には、execute は "0E0" を返します。 Perl はこれを 0 として扱いますが、真と判定します。 影響を受けた行が無いこと自体はエラーではないことに注意してください。 影響を受けた行の数がわからなければ、execute は -1 を返します。

For SELECT statements, execute simply "starts" the query within the database engine. Use one of the fetch methods to retrieve the data after calling execute. The execute method does not return the number of rows that will be returned by the query (because most databases can't tell in advance), it simply returns a true value.

SELECT 文では execute は問い合わせを単にエンジンで「開始」するだけです。 execute を呼び出した後は、fetch メソッドのどれかを使ってデータを 取り出してください。 execute メソッドは問い合わせによって返される行の数を 返しません (というのもほとんどのエンジンは前もって教えてくれないからです); それは単に真を返します。

You can tell if the statement was a SELECT statement by checking if $sth->{NUM_OF_FIELDS} is greater than zero after calling execute.

You can tell if the statement was a SELECT statement by checking if $sth->{NUM_OF_FIELDS} is greater than zero after calling execute. (TBT)

If any arguments are given, then execute will effectively call "bind_param" for each value before executing the statement. Values bound in this way are usually treated as SQL_VARCHAR types unless the driver can determine the correct type (which is rare), or unless bind_param (or bind_param_inout) has already been used to specify the type.

何か引数が与えられると、execute は、その文を実行する前に、 それぞれについて効率よく "bind_param" を呼び出します。 このようにして結び付けられた値は、ドライバが正しい型を判定できるか (判定できることはまれです)、既に bind_param(または bind_param_inout)が型を特定するために使われていなければ、通常 SQL_VARCHAR タイプとして扱われます。

Note that passing execute an empty array is the same as passing no arguments at all, which will execute the statement with previously bound values. That's probably not what you want.

Note that passing execute an empty array is the same as passing no arguments at all, which will execute the statement with previously bound values. That's probably not what you want. (TBT)

If execute() is called on a statement handle that's still active ($sth->{Active} is true) then it should effectively call finish() to tidy up the previous execution results before starting this new execution.

If execute() is called on a statement handle that's still active ($sth->{Active} is true) then it should effectively call finish() to tidy up the previous execution results before starting this new execution. (TBT)

execute_array

  $tuples = $sth->execute_array(\%attr) or die $sth->errstr;
  $tuples = $sth->execute_array(\%attr, @bind_values) or die $sth->errstr;

  ($tuples, $rows) = $sth->execute_array(\%attr) or die $sth->errstr;
  ($tuples, $rows) = $sth->execute_array(\%attr, @bind_values) or die $sth->errstr;

Execute the prepared statement once for each parameter tuple (group of values) provided either in the @bind_values, or by prior calls to "bind_param_array", or via a reference passed in \%attr.

Execute the prepared statement once for each parameter tuple (group of values) provided either in the @bind_values, or by prior calls to "bind_param_array", or via a reference passed in \%attr. (TBT)

When called in scalar context the execute_array() method returns the number of tuples executed, or undef if an error occurred. Like execute(), a successful execute_array() always returns true regardless of the number of tuples executed, even if it's zero. If there were any errors the ArrayTupleStatus array can be used to discover which tuples failed and with what errors.

When called in scalar context the execute_array() method returns the number of tuples executed, or undef if an error occurred. Like execute(), a successful execute_array() always returns true regardless of the number of tuples executed, even if it's zero. If there were any errors the ArrayTupleStatus array can be used to discover which tuples failed and with what errors. (TBT)

When called in list context the execute_array() method returns two scalars; $tuples is the same as calling execute_array() in scalar context and $rows is the sum of the number of rows affected for each tuple, if available or -1 if the driver cannot determine this. If you are doing an update operation the returned rows affected may not be what you expect if, for instance, one or more of the tuples affected the same row multiple times. Some drivers may not yet support list context, in which case $rows will be undef, or may not be able to provide the number of rows affected when performing this batch operation, in which case $rows will be -1.

When called in list context the execute_array() method returns two scalars; $tuples is the same as calling execute_array() in scalar context and $rows is the sum of the number of rows affected for each tuple, if available or -1 if the driver cannot determine this. If you are doing an update operation the returned rows affected may not be what you expect if, for instance, one or more of the tuples affected the same row multiple times. Some drivers may not yet support list context, in which case $rows will be undef, or may not be able to provide the number of rows affected when performing this batch operation, in which case $rows will be -1. (TBT)

Bind values for the tuples to be executed may be supplied row-wise by an ArrayTupleFetch attribute, or else column-wise in the @bind_values argument, or else column-wise by prior calls to "bind_param_array".

Bind values for the tuples to be executed may be supplied row-wise by an ArrayTupleFetch attribute, or else column-wise in the @bind_values argument, or else column-wise by prior calls to "bind_param_array". (TBT)

Where column-wise binding is used (via the @bind_values argument or calls to bind_param_array()) the maximum number of elements in any one of the bound value arrays determines the number of tuples executed. Placeholders with fewer values in their parameter arrays are treated as if padded with undef (NULL) values.

Where column-wise binding is used (via the @bind_values argument or calls to bind_param_array()) the maximum number of elements in any one of the bound value arrays determines the number of tuples executed. Placeholders with fewer values in their parameter arrays are treated as if padded with undef (NULL) values. (TBT)

If a scalar value is bound, instead of an array reference, it is treated as a variable length array with all elements having the same value. It does not influence the number of tuples executed, so if all bound arrays have zero elements then zero tuples will be executed. If all bound values are scalars then one tuple will be executed, making execute_array() act just like execute().

If a scalar value is bound, instead of an array reference, it is treated as a variable length array with all elements having the same value. It does not influence the number of tuples executed, so if all bound arrays have zero elements then zero tuples will be executed. If all bound values are scalars then one tuple will be executed, making execute_array() act just like execute(). (TBT)

The ArrayTupleFetch attribute can be used to specify a reference to a subroutine that will be called to provide the bind values for each tuple execution. The subroutine should return an reference to an array which contains the appropriate number of bind values, or return an undef if there is no more data to execute.

The ArrayTupleFetch attribute can be used to specify a reference to a subroutine that will be called to provide the bind values for each tuple execution. The subroutine should return an reference to an array which contains the appropriate number of bind values, or return an undef if there is no more data to execute. (TBT)

As a convenience, the ArrayTupleFetch attribute can also be used to specify a statement handle. In which case the fetchrow_arrayref() method will be called on the given statement handle in order to provide the bind values for each tuple execution.

As a convenience, the ArrayTupleFetch attribute can also be used to specify a statement handle. In which case the fetchrow_arrayref() method will be called on the given statement handle in order to provide the bind values for each tuple execution. (TBT)

The values specified via bind_param_array() or the @bind_values parameter may be either scalars, or arrayrefs. If any @bind_values are given, then execute_array will effectively call "bind_param_array" for each value before executing the statement. Values bound in this way are usually treated as SQL_VARCHAR types unless the driver can determine the correct type (which is rare), or unless bind_param, bind_param_inout, bind_param_array, or bind_param_inout_array has already been used to specify the type. See "bind_param_array" for details.

The values specified via bind_param_array() or the @bind_values parameter may be either scalars, or arrayrefs. If any @bind_values are given, then execute_array will effectively call "bind_param_array" for each value before executing the statement. Values bound in this way are usually treated as SQL_VARCHAR types unless the driver can determine the correct type (which is rare), or unless bind_param, bind_param_inout, bind_param_array, or bind_param_inout_array has already been used to specify the type. See "bind_param_array" for details. (TBT)

The ArrayTupleStatus attribute can be used to specify a reference to an array which will receive the execute status of each executed parameter tuple. Note the ArrayTupleStatus attribute was mandatory until DBI 1.38.

The ArrayTupleStatus attribute can be used to specify a reference to an array which will receive the execute status of each executed parameter tuple. Note the ArrayTupleStatus attribute was mandatory until DBI 1.38. (TBT)

For tuples which are successfully executed, the element at the same ordinal position in the status array is the resulting rowcount. If the execution of a tuple causes an error, then the corresponding status array element will be set to a reference to an array containing the error code and error string set by the failed execution.

For tuples which are successfully executed, the element at the same ordinal position in the status array is the resulting rowcount. If the execution of a tuple causes an error, then the corresponding status array element will be set to a reference to an array containing the error code and error string set by the failed execution. (TBT)

If any tuple execution returns an error, execute_array will return undef. In that case, the application should inspect the status array to determine which parameter tuples failed. Some databases may not continue executing tuples beyond the first failure. In this case the status array will either hold fewer elements, or the elements beyond the failure will be undef.

If any tuple execution returns an error, execute_array will return undef. In that case, the application should inspect the status array to determine which parameter tuples failed. Some databases may not continue executing tuples beyond the first failure. In this case the status array will either hold fewer elements, or the elements beyond the failure will be undef. (TBT)

If all parameter tuples are successfully executed, execute_array returns the number tuples executed. If no tuples were executed, then execute_array() returns "0E0", just like execute() does, which Perl will treat as 0 but will regard as true.

If all parameter tuples are successfully executed, execute_array returns the number tuples executed. If no tuples were executed, then execute_array() returns "0E0", just like execute() does, which Perl will treat as 0 but will regard as true. (TBT)

For example:

例えば:

  $sth = $dbh->prepare("INSERT INTO staff (first_name, last_name) VALUES (?, ?)");
  my $tuples = $sth->execute_array(
      { ArrayTupleStatus => \my @tuple_status },
      \@first_names,
      \@last_names,
  );
  if ($tuples) {
      print "Successfully inserted $tuples records\n";
  }
  else {
      for my $tuple (0..@last_names-1) {
          my $status = $tuple_status[$tuple];
          $status = [0, "Skipped"] unless defined $status;
          next unless ref $status;
          printf "Failed to insert (%s, %s): %s\n",
              $first_names[$tuple], $last_names[$tuple], $status->[1];
      }
  }

Support for data returning statements such as SELECT is driver-specific and subject to change. At present, the default implementation provided by DBI only supports non-data returning statements.

Support for data returning statements such as SELECT is driver-specific and subject to change. At present, the default implementation provided by DBI only supports non-data returning statements. (TBT)

Transaction semantics when using array binding are driver and database specific. If AutoCommit is on, the default DBI implementation will cause each parameter tuple to be individually committed (or rolled back in the event of an error). If AutoCommit is off, the application is responsible for explicitly committing the entire set of bound parameter tuples. Note that different drivers and databases may have different behaviours when some parameter tuples cause failures. In some cases, the driver or database may automatically rollback the effect of all prior parameter tuples that succeeded in the transaction; other drivers or databases may retain the effect of prior successfully executed parameter tuples. Be sure to check your driver and database for its specific behaviour.

Transaction semantics when using array binding are driver and database specific. If AutoCommit is on, the default DBI implementation will cause each parameter tuple to be individually committed (or rolled back in the event of an error). If AutoCommit is off, the application is responsible for explicitly committing the entire set of bound parameter tuples. Note that different drivers and databases may have different behaviours when some parameter tuples cause failures. In some cases, the driver or database may automatically rollback the effect of all prior parameter tuples that succeeded in the transaction; other drivers or databases may retain the effect of prior successfully executed parameter tuples. Be sure to check your driver and database for its specific behaviour. (TBT)

Note that, in general, performance will usually be better with AutoCommit turned off, and using explicit commit after each execute_array call.

Note that, in general, performance will usually be better with AutoCommit turned off, and using explicit commit after each execute_array call. (TBT)

The execute_array method was added in DBI 1.22, and ArrayTupleFetch was added in 1.36.

execute_array メソッドは DBI 1.22 で追加され、ArrayTupleFetch は 1.36 で追加されました。

execute_for_fetch

  $tuples = $sth->execute_for_fetch($fetch_tuple_sub);
  $tuples = $sth->execute_for_fetch($fetch_tuple_sub, \@tuple_status);

  ($tuples, $rows) = $sth->execute_for_fetch($fetch_tuple_sub);
  ($tuples, $rows) = $sth->execute_for_fetch($fetch_tuple_sub, \@tuple_status);

The execute_for_fetch() method is used to perform bulk operations and is most often used via the execute_array() method, not directly.

The execute_for_fetch() method is used to perform bulk operations and is most often used via the execute_array() method, not directly. (TBT)

The fetch subroutine, referenced by $fetch_tuple_sub, is expected to return a reference to an array (known as a 'tuple') or undef.

The fetch subroutine, referenced by $fetch_tuple_sub, is expected to return a reference to an array (known as a 'tuple') or undef. (TBT)

The execute_for_fetch() method calls $fetch_tuple_sub, without any parameters, until it returns a false value. Each tuple returned is used to provide bind values for an $sth->execute(@$tuple) call.

The execute_for_fetch() method calls $fetch_tuple_sub, without any parameters, until it returns a false value. Each tuple returned is used to provide bind values for an $sth->execute(@$tuple) call. (TBT)

In scalar context execute_for_fetch() returns undef if there were any errors and the number of tuples executed otherwise. Like execute() and execute_array() a zero is returned as "0E0" so execute_for_fetch() is only false on error. If there were any errors the @tuple_status array can be used to discover which tuples failed and with what errors.

In scalar context execute_for_fetch() returns undef if there were any errors and the number of tuples executed otherwise. Like execute() and execute_array() a zero is returned as "0E0" so execute_for_fetch() is only false on error. If there were any errors the @tuple_status array can be used to discover which tuples failed and with what errors. (TBT)

When called in list context execute_for_fetch() returns two scalars; $tuples is the same as calling execute_for_fetch() in scalar context and $rows is the sum of the number of rows affected for each tuple, if available or -1 if the driver cannot determine this. If you are doing an update operation the returned rows affected may not be what you expect if, for instance, one or more of the tuples affected the same row multiple times. Some drivers may not yet support list context, in which case $rows will be undef, or may not be able to provide the number of rows affected when performing this batch operation, in which case $rows will be -1.

When called in list context execute_for_fetch() returns two scalars; $tuples is the same as calling execute_for_fetch() in scalar context and $rows is the sum of the number of rows affected for each tuple, if available or -1 if the driver cannot determine this. If you are doing an update operation the returned rows affected may not be what you expect if, for instance, one or more of the tuples affected the same row multiple times. Some drivers may not yet support list context, in which case $rows will be undef, or may not be able to provide the number of rows affected when performing this batch operation, in which case $rows will be -1. (TBT)

If \@tuple_status is passed then the execute_for_fetch method uses it to return status information. The tuple_status array holds one element per tuple. If the corresponding execute() did not fail then the element holds the return value from execute(), which is typically a row count. If the execute() did fail then the element holds a reference to an array containing ($sth->err, $sth->errstr, $sth->state).

If \@tuple_status is passed then the execute_for_fetch method uses it to return status information. The tuple_status array holds one element per tuple. If the corresponding execute() did not fail then the element holds the return value from execute(), which is typically a row count. If the execute() did fail then the element holds a reference to an array containing ($sth->err, $sth->errstr, $sth->state). (TBT)

If the driver detects an error that it knows means no further tuples can be executed then it may return, with an error status, even though $fetch_tuple_sub may still have more tuples to be executed.

If the driver detects an error that it knows means no further tuples can be executed then it may return, with an error status, even though $fetch_tuple_sub may still have more tuples to be executed. (TBT)

Although each tuple returned by $fetch_tuple_sub is effectively used to call $sth->execute(@$tuple_array_ref) the exact timing may vary. Drivers are free to accumulate sets of tuples to pass to the database server in bulk group operations for more efficient execution. However, the $fetch_tuple_sub is specifically allowed to return the same array reference each time (which is what fetchrow_arrayref() usually does).

Although each tuple returned by $fetch_tuple_sub is effectively used to call $sth->execute(@$tuple_array_ref) the exact timing may vary. Drivers are free to accumulate sets of tuples to pass to the database server in bulk group operations for more efficient execution. However, the $fetch_tuple_sub is specifically allowed to return the same array reference each time (which is what fetchrow_arrayref() usually does). (TBT)

For example:

例えば:

  my $sel = $dbh1->prepare("select foo, bar from table1");
  $sel->execute;

  my $ins = $dbh2->prepare("insert into table2 (foo, bar) values (?,?)");
  my $fetch_tuple_sub = sub { $sel->fetchrow_arrayref };

  my @tuple_status;
  $rc = $ins->execute_for_fetch($fetch_tuple_sub, \@tuple_status);
  my @errors = grep { ref $_ } @tuple_status;

Similarly, if you already have an array containing the data rows to be processed you'd use a subroutine to shift off and return each array ref in turn:

Similarly, if you already have an array containing the data rows to be processed you'd use a subroutine to shift off and return each array ref in turn: (TBT)

  $ins->execute_for_fetch( sub { shift @array_of_arrays }, \@tuple_status);

The execute_for_fetch method was added in DBI 1.38.

execute_for_fetch メソッドは DBI 1.38 で追加されました。

fetchrow_arrayref

  $ary_ref = $sth->fetchrow_arrayref;
  $ary_ref = $sth->fetch;    # alias

Fetches the next row of data and returns a reference to an array holding the field values. Null fields are returned as undef values in the array. This is the fastest way to fetch data, particularly if used with $sth->bind_columns.

次のデータの行を取り出し、フィールドの値をもった配列へのリファレンスを 返します。 Null のフィールドは undef で返されます。 特に $sth->bind_columns を使っているならば、これがデータを取り出す 最も速い方法です。

If there are no more rows or if an error occurs, then fetchrow_arrayref returns an undef. You should check $sth->err afterwards (or use the RaiseError attribute) to discover if the undef returned was due to an error.

もう行が無いか、エラーが発生すると、fetchrow_arrayrefundef を返します。 後で返された undef がエラーによるものかどうかを見るために、 $sth->err をチェックするべきです(あるいは RaiseError 属性を 使うか)。

Note that the same array reference is returned for each fetch, so don't store the reference and then use it after a later fetch. Also, the elements of the array are also reused for each row, so take care if you want to take a reference to an element. See also "bind_columns".

現状では、データを取り出すたびに同じ配列リファレンスが返されることが あることに注意してください。 そのためリファレンスを取っておいて、データの取り出しを進めた後で、 使わないでください。 同様に配列の要素も各行で再使用されます。 要素のリファレンスを取得したいならば、注意してください。 "bind_columns" もご覧ください。

fetchrow_array

 @ary = $sth->fetchrow_array;

An alternative to fetchrow_arrayref. Fetches the next row of data and returns it as a list containing the field values. Null fields are returned as undef values in the list.

fetchrow_arrayref の代用品です。 次のデータ行を取り出し、フィールドの値を持った配列を返します。 Null のフィールドはリストの中の undef 値として返されます。

If there are no more rows or if an error occurs, then fetchrow_array returns an empty list. You should check $sth->err afterwards (or use the RaiseError attribute) to discover if the empty list returned was due to an error.

もう行が無いか、エラーが発生すると、fetchrow_array は空リストを返します。 後で返された空リストがエラーによるものかどうかを見るために、 $sth->err をチェックするべきです(あるいは RaiseError 属性を 使うか)。

If called in a scalar context for a statement handle that has more than one column, it is undefined whether the driver will return the value of the first column or the last. So don't do that. Also, in a scalar context, an undef is returned if there are no more rows or if an error occurred. That undef can't be distinguished from an undef returned because the first field value was NULL. For these reasons you should exercise some caution if you use fetchrow_array in a scalar context.

If called in a scalar context for a statement handle that has more than one column, it is undefined whether the driver will return the value of the first column or the last. So don't do that. また、スカラコンテキストでは、もう行がないか、エラーが発生すると undef が返されます。 この undef を最初のフィールドの値が NULL のために返される undef とは 区別することは出来ません。 これらの理由により、fetchrow_array をスカラコンテキストで使うならば 注意を払う必要があります。 (TBT)

fetchrow_hashref

 $hash_ref = $sth->fetchrow_hashref;
 $hash_ref = $sth->fetchrow_hashref($name);

An alternative to fetchrow_arrayref. Fetches the next row of data and returns it as a reference to a hash containing field name and field value pairs. Null fields are returned as undef values in the hash.

fetchrow_arrayref の代用品です。 次のデータ行を取り出し、フィールドの名前と値のペアを持ったハッシュへの リファレンスを返します。 NULL フィールドはハッシュのなかの undef として返されます。

If there are no more rows or if an error occurs, then fetchrow_hashref returns an undef. You should check $sth->err afterwards (or use the RaiseError attribute) to discover if the undef returned was due to an error.

もう行が無いか、エラーが発生すると、fetchrow_hashrefundef を 返します。 後で返された undef がエラーによるものかどうかを見るために、 $sth->err をチェックするべきです(あるいは RaiseError 属性を 使うか)。

The optional $name parameter specifies the name of the statement handle attribute. For historical reasons it defaults to "NAME", however using either "NAME_lc" or "NAME_uc" is recommended for portability.

オプションの $name パラメータには、文ハンドル属性の名前を 指定します。 移植性の面からは "NAME_lc" や "NAME_uc" を使うことが勧められるのですが、 歴史的な理由から、デフォルトは "NAME" になります。

The keys of the hash are the same names returned by $sth->{$name}. If more than one field has the same name, there will only be one entry in the returned hash for those fields, so statements like "select foo, foo from bar" will return only a single key from fetchrow_hashref. In these cases use column aliases or fetchrow_arrayref. Note that it is the database server (and not the DBD implementation) which provides the name for fields containing functions like "count(*)" or "max(c_foo)" and they may clash with existing column names (most databases don't care about duplicate column names in a result-set). If you want these to return as unique names that are the same across databases, use aliases, as in "select count(*) as cnt" or "select max(c_foo) mx_foo, ..." depending on the syntax your database supports.

ハッシュのキーは $sth->{$name} によって返される名前と同じです。 複数のフィールドが同じ名前であった場合、返されたハッシュの中のそれらの フィールドためのエントリはただ一つになるので、 so statements like "select foo, foo from bar" will return only a single key from fetchrow_hashref. In these cases use column aliases or fetchrow_arrayref. Note that it is the database server (and not the DBD implementation) which provides the name for fields containing functions like "count(*)" or "max(c_foo)" and they may clash with existing column names (most databases don't care about duplicate column names in a result-set). If you want these to return as unique names that are the same across databases, use aliases, as in "select count(*) as cnt" or "select max(c_foo) mx_foo, ..." depending on the syntax your database supports. (TBT)

Because of the extra work fetchrow_hashref and Perl have to perform, it is not as efficient as fetchrow_arrayref or fetchrow_array.

fetchrow_hashref は追加の動作をし、さらに Perl が動かなければならないので、 fetchrow_arrayreffetchrow_array ほど効率よくありません。

By default a reference to a new hash is returned for each row. It is likely that a future version of the DBI will support an attribute which will enable the same hash to be reused for each row. This will give a significant performance boost, but it won't be enabled by default because of the risk of breaking old code.

デフォルトでは行毎に新しいハッシュリファレンスが返されます。 将来のバージョンの DBI では行毎に同じハッシュを再利用することを有効にする 新しい属性に対応する予定です。 これは大きく性能を改善させますが、古いコードを壊すリスクがあるので デフォルトでは有効にならない予定です。

fetchall_arrayref

  $tbl_ary_ref = $sth->fetchall_arrayref;
  $tbl_ary_ref = $sth->fetchall_arrayref( $slice );
  $tbl_ary_ref = $sth->fetchall_arrayref( $slice, $max_rows  );

The fetchall_arrayref method can be used to fetch all the data to be returned from a prepared and executed statement handle. It returns a reference to an array that contains one reference per row.

fetchall_arrayref メソッドは prepare され、execute された 文ハンドルから、返されるべきすべてのデータを取り出すために 使います。 1 行につき一つのリファレンスが入っている配列へのリファレンスを返します。

If there are no rows to return, fetchall_arrayref returns a reference to an empty array. If an error occurs, fetchall_arrayref returns the data fetched thus far, which may be none. You should check $sth->err afterwards (or use the RaiseError attribute) to discover if the data is complete or was truncated due to an error.

もう行が無いかエラーが発生すると、fetchall_arrayref は空の配列への リファレンスを返します。 エラーが発生したら、fetchall_arrayref はデータを取り出せたところまで 返します(これは空であるかもしれません)。 データが完全であるか、エラーにより切り捨てられたかを見るために、後で $sth->err をチェックするべきです(あるいは RaiseError 属性を 使うか)。

If $slice is an array reference, fetchall_arrayref uses "fetchrow_arrayref" to fetch each row as an array ref. If the $slice array is not empty then it is used as a slice to select individual columns by perl array index number (starting at 0, unlike column and parameter numbers which start at 1).

$slice が配列リファレンスなら、fetchall_arrayref"fetchrow_arrayref" を使って配列のリファレンスで各行を取り出します。 もし $slice の配列が空でなければ、perl 配列インデックス番号 (0 から始まります; 1 から始まる列やパラメータの番号とは違います) によってそれぞれの列を選択し切り出すために使われます。

With no parameters, or if $slice is undefined, fetchall_arrayref acts as if passed an empty array ref.

パラメータがないか、$slice が未定義値なら、fetchall_arrayref は 空の配列リファレンスが渡されたように動きます。

If $slice is a hash reference, fetchall_arrayref uses "fetchrow_hashref" to fetch each row as a hash reference. If the $slice hash is empty then fetchrow_hashref() is simply called in a tight loop and the keys in the hashes have whatever name lettercase is returned by default from fetchrow_hashref. (See "FetchHashKeyName" attribute.) If the $slice hash is not empty, then it is used as a slice to select individual columns by name. The values of the hash should be set to 1. The key names of the returned hashes match the letter case of the names in the parameter hash, regardless of the "FetchHashKeyName" attribute.

$slice がハッシュのリファレンスなら、fetchall_arrayref"fetchrow_hashref" を使って、各行をハッシュのリファレンスで取り出します。 $slice ハッシュが空なら、fetchrow_hashref は単にきついループで 呼ばれるだけで、ハッシュのキーは fetchrow_hashref からのデフォルトで 返されるすべての小文字の名前を持つだけです ("FetchHashKeyName" 属性をご覧ください)。 $slice ハッシュが空でなければ、名前で個々の列を選択するためのスライスとして 使われます。 ハッシュの値は 1 に設定されるべきです。 かえされたハッシュのキー名は、"FetchHashKeyName" 属性にかかわらず パラメータハッシュの名前の小文字とマッチングされます。

For example, to fetch just the first column of every row:

例えば、各行の先頭の列だけを取り出したい場合は:

  $tbl_ary_ref = $sth->fetchall_arrayref([0]);

To fetch the second to last and last column of every row:

各行の一番後ろ、その直前の列を取り出すには:

  $tbl_ary_ref = $sth->fetchall_arrayref([-2,-1]);

To fetch all fields of every row as a hash ref:

各行をハッシュリファレンスとして取り出すためには:

  $tbl_ary_ref = $sth->fetchall_arrayref({});

To fetch only the fields called "foo" and "bar" of every row as a hash ref (with keys named "foo" and "BAR"):

("foo" および "BAR" というキー名で) 各行の "foo" と "bar" という フィールドだけを取り出すためには:

  $tbl_ary_ref = $sth->fetchall_arrayref({ foo=>1, BAR=>1 });

The first two examples return a reference to an array of array refs. The third and forth return a reference to an array of hash refs.

最初の二つの例では、配列リファレンスの配列へのリファレンスを返します。 3 番目と 4 番目の例はハッシュリファレンスの配列へのリファレンスを返します。

If $max_rows is defined and greater than or equal to zero then it is used to limit the number of rows fetched before returning. fetchall_arrayref() can then be called again to fetch more rows. This is especially useful when you need the better performance of fetchall_arrayref() but don't have enough memory to fetch and return all the rows in one go.

If $max_rows is defined and greater than or equal to zero then it is used to limit the number of rows fetched before returning. fetchall_arrayref() can then be called again to fetch more rows. This is especially useful when you need the better performance of fetchall_arrayref() but don't have enough memory to fetch and return all the rows in one go. (TBT)

Here's an example (assumes RaiseError is enabled):

以下は例です(RaiseError が有効であることを仮定しています):

  my $rows = []; # cache for batches of rows
  while( my $row = ( shift(@$rows) || # get row from cache, or reload cache:
                     shift(@{$rows=$sth->fetchall_arrayref(undef,10_000)||[]}) )
  ) {
    ...
  }

That might be the fastest way to fetch and process lots of rows using the DBI, but it depends on the relative cost of method calls vs memory allocation.

これは DBI を使ってたくさんの列をフェッチして処理するための最速の方法 かもしれません が、メソッド呼び出し対メモリ割り当ての相対コストに 依存します。

A standard while loop with column binding is often faster because the cost of allocating memory for the batch of rows is greater than the saving by reducing method calls. It's possible that the DBI may provide a way to reuse the memory of a previous batch in future, which would then shift the balance back towards fetchall_arrayref().

A standard while loop with column binding is often faster because the cost of allocating memory for the batch of rows is greater than the saving by reducing method calls. It's possible that the DBI may provide a way to reuse the memory of a previous batch in future, which would then shift the balance back towards fetchall_arrayref(). (TBT)

fetchall_hashref

  $hash_ref = $sth->fetchall_hashref($key_field);

The fetchall_hashref method can be used to fetch all the data to be returned from a prepared and executed statement handle. It returns a reference to a hash containing a key for each distinct value of the $key_field column that was fetched. For each key the corresponding value is a reference to a hash containing all the selected columns and their values, as returned by fetchrow_hashref().

The fetchall_hashref method can be used to fetch all the data to be returned from a prepared and executed statement handle. It returns a reference to a hash containing a key for each distinct value of the $key_field column that was fetched. For each key the corresponding value is a reference to a hash containing all the selected columns and their values, as returned by fetchrow_hashref(). (TBT)

If there are no rows to return, fetchall_hashref returns a reference to an empty hash. If an error occurs, fetchall_hashref returns the data fetched thus far, which may be none. You should check $sth->err afterwards (or use the RaiseError attribute) to discover if the data is complete or was truncated due to an error.

If there are no rows to return, fetchall_hashref returns a reference to an empty hash. If an error occurs, fetchall_hashref returns the data fetched thus far, which may be none. You should check $sth->err afterwards (or use the RaiseError attribute) to discover if the data is complete or was truncated due to an error. (TBT)

The $key_field parameter provides the name of the field that holds the value to be used for the key for the returned hash. For example:

$key_field パラメータは返されたハッシュのキーのために使われる値を 保持するフィールド名を提供します。 例えば:

  $dbh->{FetchHashKeyName} = 'NAME_lc';
  $sth = $dbh->prepare("SELECT FOO, BAR, ID, NAME, BAZ FROM TABLE");
  $sth->execute;
  $hash_ref = $sth->fetchall_hashref('id');
  print "Name for id 42 is $hash_ref->{42}->{name}\n";

The $key_field parameter can also be specified as an integer column number (counting from 1). If $key_field doesn't match any column in the statement, as a name first then as a number, then an error is returned.

The $key_field parameter can also be specified as an integer column number (counting from 1). If $key_field doesn't match any column in the statement, as a name first then as a number, then an error is returned. (TBT)

For queries returning more than one 'key' column, you can specify multiple column names by passing $key_field as a reference to an array containing one or more key column names (or index numbers). For example:

For queries returning more than one 'key' column, you can specify multiple column names by passing $key_field as a reference to an array containing one or more key column names (or index numbers). For example: (TBT)

  $sth = $dbh->prepare("SELECT foo, bar, baz FROM table");
  $sth->execute;
  $hash_ref = $sth->fetchall_hashref( [ qw(foo bar) ] );
  print "For foo 42 and bar 38, baz is $hash_ref->{42}->{38}->{baz}\n";

The fetchall_hashref() method is normally used only where the key fields values for each row are unique. If multiple rows are returned with the same values for the key fields then later rows overwrite earlier ones.

The fetchall_hashref() method is normally used only where the key fields values for each row are unique. If multiple rows are returned with the same values for the key fields then later rows overwrite earlier ones. (TBT)

finish

  $rc  = $sth->finish;

Indicate that no more data will be fetched from this statement handle before it is either executed again or destroyed. You almost certainly do not need to call this method.

もう一度 execute されるか、破壊されるまで、この文ハンドルからは もうデータが取り出されないことを示します。 ほぼ確実に、このメソッドを呼び出す必要は ありません

Adding calls to finish after loop that fetches all rows is a common mistake, don't do it, it can mask genuine problems like uncaught fetch errors.

全ての行をフェッチしたループの後に finish 呼び出しを追加するのは よくある間違いです; 捕捉されていないフェッチのエラーのような本当の問題を 隠してしまうかもしれないので、そうしてはいけません。

When all the data has been fetched from a SELECT statement, the driver will automatically call finish for you. So you should not call it explicitly except when you know that you've not fetched all the data from a statement handle and the handle won't be destroyed soon.

すべてのデータが SELECT 文から取り出されたら、ドライバは 自動的にあなたに代って finish します。 そのため、文ハンドルから全てのデータを取り出しておらず、 かつ ハンドルがすぐには破壊されない場合 以外は これを明示的に呼び出すべきでは ありません

The most common example is when you only want to fetch just one row, but in that case the selectrow_* methods are usually better anyway.

もっともよくある例は、たった 1 行だけをフェッチしたいだけの場合ですが、 その場合は selectrow_* メソッドの方が普通は優れています。

Consider a query like:

以下のような問い合わせを考えてみてください:

  SELECT foo FROM table WHERE bar=? ORDER BY baz

on a very large table. When executed, the database server will have to use temporary buffer space to store the sorted rows. If, after executing the handle and selecting just a few rows, the handle won't be re-executed for some time and won't be destroyed, the finish method can be used to tell the server that the buffer space can be freed.

これをとても大きなテーブルに対して行います。 実行されるとデータベースサーバは一時的なバッファ領域をソートされた行を 格納するために使わなければなりません。 もし実行し、数行選択した後で、しばらくハンドルが再実行されなかったり、 破壊されないならば、finish メソッドによってサーバにバッファ領域を 解放することができることを教えることができます。

Calling finish resets the "Active" attribute for the statement. It may also make some statement handle attributes (such as NAME and TYPE) unavailable if they have not already been accessed (and thus cached).

finish を呼び出すと、その文の "Active" 属性は リセットされます。 (NAMETYPE のような)他の文ハンドル属性のいくつかも、 既にアクセスされて(そしてキャッシュされて)いるのでなければ、 使用できなくなるかもしれません。

The finish method does not affect the transaction status of the database connection. It has nothing to do with transactions. It's mostly an internal "housekeeping" method that is rarely needed. See also "disconnect" and the "Active" attribute.

finish メソッドはデータベース接続のトランザクションの状態にはなにも 影響を与えません。 トランザクションとは無関係です。 これはほとんど内部の「家事的(='housekeeping')」メソッドで、あまり 必要なことはありません。 "disconnect""Active" 属性もご覧ください。

The finish method should have been called discard_pending_rows.

finish メソッドは discard_pending_rows と呼ばれるべきでした。

rows

  $rv = $sth->rows;

Returns the number of rows affected by the last row affecting command, or -1 if the number of rows is not known or not available.

最後のコマンドにより影響を受けた行数を返します。 不明または使用不能の場合は -1 になります。

Generally, you can only rely on a row count after a non-SELECT execute (for some specific operations like UPDATE and DELETE), or after fetching all the rows of a SELECT statement.

通常、行カウントは SELECT (UPDATEDELETE のような 特定の操作)の execute または、SELECT 文のすべての行を 取り出した後にしか、信用できません。

For SELECT statements, it is generally not possible to know how many rows will be returned except by fetching them all. Some drivers will return the number of rows the application has fetched so far, but others may return -1 until all rows have been fetched. So use of the rows method or $DBI::rows with SELECT statements is not recommended.

SELECT 文では、通常、何行返ってくるのかは、すべてを 取り出すまではわかりません。 ドライバによってはそれまでに取得した行数を返すものもありますが、 すべての行が取り出されるまでは -1 を返すものもあります。 そのため SELECT 文に rows メソッドや $DBI::rows を 使うことはお勧めできません。

One alternative method to get a row count for a SELECT is to execute a "SELECT COUNT(*) FROM ..." SQL statement with the same "..." as your query and then fetch the row count from that.

SELECT の行カウントを得るための代わりの方法の一つは、 "SELECT COUNT(*) FROM ..." 文を、"..."をあなたの問い合わせと 同じにして実行し、それから行数を取り出すことです。

bind_col

  $rc = $sth->bind_col($column_number, \$var_to_bind);
  $rc = $sth->bind_col($column_number, \$var_to_bind, \%attr );
  $rc = $sth->bind_col($column_number, \$var_to_bind, $bind_type );

Binds a Perl variable and/or some attributes to an output column (field) of a SELECT statement. Column numbers count up from 1. You do not need to bind output columns in order to fetch data. For maximum portability between drivers, bind_col() should be called after execute() and not before. See also bind_columns for an example.

SELECT 文の出力カラム(フィールド)にperlの変数と属性を結び付けます。 カラム番号は1から数えます。 Binds a Perl variable and/or some attributes to an output column (field) of a SELECT statement. Column numbers count up from 1. You do not need to bind output columns in order to fetch data. For maximum portability between drivers, bind_col() should be called after execute() and not before. 例として下記の bind_columns をご覧下さい。 (TBT)

The binding is performed at a low level using Perl aliasing. Whenever a row is fetched from the database $var_to_bind appears to be automatically updated simply because it now refers to the same memory location as the corresponding column value. This makes using bound variables very efficient. Binding a tied variable doesn't work, currently.

バインディングは Perl エイリアスを使い、下位のレベルで実行されます。 データベースから行が取り出されると、$var_to_bind が自動的に更新されます because it now refers to the same memory location as the corresponding column value. これはバインドされた変数を非常に効率よく使います。 tie された変数へのバインディングは現在のところ動作しません。 (TBT)

The "bind_param" method performs a similar, but opposite, function for input variables.

The "bind_param" method performs a similar, but opposite, function for input variables. (TBT)

Data Types for Column Binding

列バインディングのためのデータ型

The \%attr parameter can be used to hint at the data type formatting the column should have. For example, you can use:

The \%attr parameter can be used to hint at the data type formatting the column should have. For example, you can use: (TBT)

  $sth->bind_col(1, undef, { TYPE => SQL_DATETIME });

to specify that you'd like the column (which presumably is some kind of datetime type) to be returned in the standard format for SQL_DATETIME, which is 'YYYY-MM-DD HH:MM:SS', rather than the native formatting the database would normally use.

to specify that you'd like the column (which presumably is some kind of datetime type) to be returned in the standard format for SQL_DATETIME, which is 'YYYY-MM-DD HH:MM:SS', rather than the native formatting the database would normally use. (TBT)

There's no $var_to_bind in that example to emphasize the point that bind_col() works on the underlying column and not just a particular bound variable.

There's no $var_to_bind in that example to emphasize the point that bind_col() works on the underlying column and not just a particular bound variable. (TBT)

As a short-cut for the common case, the data type can be passed directly, in place of the \%attr hash reference. This example is equivalent to the one above:

As a short-cut for the common case, the data type can be passed directly, in place of the \%attr hash reference. This example is equivalent to the one above: (TBT)

  $sth->bind_col(1, undef, SQL_DATETIME);

The TYPE value indicates the standard (non-driver-specific) type for this parameter. To specify the driver-specific type, the driver may support a driver-specific attribute, such as { ora_type => 97 }.

The TYPE value indicates the standard (non-driver-specific) type for this parameter. To specify the driver-specific type, the driver may support a driver-specific attribute, such as { ora_type => 97 }. (TBT)

The SQL_DATETIME and other related constants can be imported using

SQL_DATETIME と関連する定数は以下のようにしてインポートできます

  use DBI qw(:sql_types);

See "DBI Constants" for more information.

さらなる情報については "DBI Constants" を参照してください。

Few drivers support specifying a data type via a bind_col call (most will simply ignore the data type). Fewer still allow the data type to be altered once set.

Few drivers support specifying a data type via a bind_col call (most will simply ignore the data type). Fewer still allow the data type to be altered once set. (TBT)

The TYPE attribute for bind_col() was first specified in DBI 1.41.

bind_col() の TYPE 属性は DBI 1.41 で最初に定義されました。

From DBI 1.611, drivers can use the TYPE attribute to attempt to cast the bound scalar to a perl type which more closely matches TYPE. At present DBI supports SQL_INTEGER, SQL_DOUBLE and SQL_NUMERIC. See "sql_type_cast" for details of how types are cast.

From DBI 1.611, drivers can use the TYPE attribute to attempt to cast the bound scalar to a perl type which more closely matches TYPE. At present DBI supports SQL_INTEGER, SQL_DOUBLE and SQL_NUMERIC. See "sql_type_cast" for details of how types are cast. (TBT)

Other attributes for Column Binding

列のバインディングのためのその他の属性

The \%attr parameter may also contain the following attributes:

\%attr パラメータには以下の属性を含めることもできます:

StrictlyTyped

If a TYPE attribute is passed to bind_col, then the driver will attempt to change the bound perl scalar to match the type more closely. If the bound value cannot be cast to the requested TYPE then by default it is left untouched and no error is generated. If you specify StrictlyTyped as 1 and the cast fails, this will generate an error.

If a TYPE attribute is passed to bind_col, then the driver will attempt to change the bound perl scalar to match the type more closely. If the bound value cannot be cast to the requested TYPE then by default it is left untouched and no error is generated. If you specify StrictlyTyped as 1 and the cast fails, this will generate an error. (TBT)

This attribute was first added in DBI 1.611. When 1.611 was released few drivers actually supported this attribute but DBD::Oracle and DBD::ODBC should from versions 1.24.

This attribute was first added in DBI 1.611. When 1.611 was released few drivers actually supported this attribute but DBD::Oracle and DBD::ODBC should from versions 1.24. (TBT)

DiscardString

When the TYPE attribute is passed to "bind_col" and the driver successfully casts the bound perl scalar to a non-string type then if DiscardString is set to 1, the string portion of the scalar will be discarded. By default, DiscardString is not set.

When the TYPE attribute is passed to "bind_col" and the driver successfully casts the bound perl scalar to a non-string type then if DiscardString is set to 1, the string portion of the scalar will be discarded. By default, DiscardString is not set. (TBT)

This attribute was first added in DBI 1.611. When 1.611 was released few drivers actually supported this attribute but DBD::Oracle and DBD::ODBC should from versions 1.24.

This attribute was first added in DBI 1.611. When 1.611 was released few drivers actually supported this attribute but DBD::Oracle and DBD::ODBC should from versions 1.24. (TBT)

bind_columns

  $rc = $sth->bind_columns(@list_of_refs_to_vars_to_bind);

Calls "bind_col" for each column of the SELECT statement.

SELECT 文の各カラムに "bind_col" を呼び出します。

The list of references should have the same number of elements as the number of columns in the SELECT statement. If it doesn't then bind_columns will bind the elements given, up to the number of columns, and then return an error.

The list of references should have the same number of elements as the number of columns in the SELECT statement. If it doesn't then bind_columns will bind the elements given, up to the number of columns, and then return an error. (TBT)

For maximum portability between drivers, bind_columns() should be called after execute() and not before.

ドライバ間の移植性を最大限に高めるためには、bind_columns() は execute() の 後に呼び出さなければなりません。

For example:

例えば:

  $dbh->{RaiseError} = 1; # do this, or check every call for errors
  $sth = $dbh->prepare(q{ SELECT region, sales FROM sales_by_region });
  $sth->execute;
  my ($region, $sales);

  # Bind Perl variables to columns:
  $rv = $sth->bind_columns(\$region, \$sales);

  # you can also use Perl's \(...) syntax (see perlref docs):
  #     $sth->bind_columns(\($region, $sales));

  # Column binding is the most efficient way to fetch data
  while ($sth->fetch) {
      print "$region: $sales\n";
  }
  $dbh->{RaiseError} = 1; # こうするか、呼び出しのたびにエラーをチェックしてください
  $sth = $dbh->prepare(q{ SELECT region, sales FROM sales_by_region });
  $sth->execute;
  my ($region, $sales);

  # Perl の変数をカラムに結び付けます:
  $rv = $sth->bind_columns(\$region, \$sales);

  # Perl の\(...) という書き方をつかうこともできます(perlref ドキュメントをご覧ください):
  #     $sth->bind_columns(\($region, $sales));

  # カラムの結びつけはデータの取り出し方では最も効率的な方法です
  while ($sth->fetch) {
      print "$region: $sales\n";
  }

For compatibility with old scripts, the first parameter will be ignored if it is undef or a hash reference.

昔のスクリプトとの互換性のために、最初の引数が undef もしくは ハッシュリファレンスであれば、無視されます。

Here's a more fancy example that binds columns to the values inside a hash (thanks to H.Merijn Brand):

カラムをハッシュの内側の値に結びつけるという、さらにすごい例を 示します(H.Merijn Brand に感謝):

  $sth->execute;
  my %row;
  $sth->bind_columns( \( @row{ @{$sth->{NAME_lc} } } ));
  while ($sth->fetch) {
      print "$row{region}: $row{sales}\n";
  }

dump_results

  $rows = $sth->dump_results($maxlen, $lsep, $fsep, $fh);

Fetches all the rows from $sth, calls DBI::neat_list for each row, and prints the results to $fh (defaults to STDOUT) separated by $lsep (default "\n"). $fsep defaults to ", " and $maxlen defaults to 35.

$sth からすべての行を取り出し、各行に DBI::neat_list を呼び出し、 その結果を $lsep (デフォルトは "\n")で区切って、$fh(デフォルトは STDOUT)に、出力します。 $fsep のデフォルトは ", "$maxlen のデフォルトは 35 です。

This method is designed as a handy utility for prototyping and testing queries. Since it uses "neat_list" to format and edit the string for reading by humans, it is not recommended for data transfer applications.

このメソッドは問い合わせのプロトタイプとテストのための簡単な ユーティリティとして設計されています。 人の目にわかりやすいように文字列の整形し、編集する "neat_list" を 使っているので、データ転送アプリケーションにはお勧めしません。

Statement Handle Attributes

This section describes attributes specific to statement handles. Most of these attributes are read-only.

このセクションでは文・ハンドルの属性について記述します。 大半の属性は読込のみです。

Changes to these statement handle attributes do not affect any other existing or future statement handles.

これらの文・ハンドル属性を変更しても、既存のほかのハンドルや後で作成される文・ハンドルには影響を与えません。

Attempting to set or get the value of an unknown attribute generates a warning, except for private driver specific attributes (which all have names starting with a lowercase letter).

ドライバ毎のプライベートな属性を除いては、決められていない属性を設定あるいは取得しようとすると致命的なエラーになります。(ドライバ毎のプライベートな属性は名前が小文字ではじまります)

Example:

例:

  ... = $h->{NUM_OF_FIELDS};    # get/read

Some drivers cannot provide valid values for some or all of these attributes until after $sth->execute has been successfully called. Typically the attribute will be undef in these situations.

ドライバによっては、$sth->execute が呼ばれるまでは、一部あるいは すべての属性について正しい値を提供できないものもあります。 典型的には、このような状況では属性は undef になります。

Some attributes, like NAME, are not appropriate to some types of statement, like SELECT. Typically the attribute will be undef in these situations.

Some attributes, like NAME, are not appropriate to some types of statement, like SELECT. Typically the attribute will be undef in these situations. (TBT)

For drivers which support stored procedures and multiple result sets (see more_results) these attributes relate to the current result set.

For drivers which support stored procedures and multiple result sets (see more_results) these attributes relate to the current result set. (TBT)

See also "finish" to learn more about the effect it may have on some attributes.

いくつかの属性に影響を与えるかもしれないことについて、より知るために "finish" もご覧ください。

NUM_OF_FIELDS (integer, read-only)

Number of fields (columns) in the data the prepared statement may return. Statements that don't return rows of data, like DELETE and CREATE set NUM_OF_FIELDS to 0 (though it may be undef in some drivers).

準備(prepare) された SQL 文のフィールド(カラム)の数を返します。 DELETECREATE のように行数を返さない文の場合 NUM_OF_FIELDS は 0 を設定します(しかしドライバによっては undef を 返します)。

NUM_OF_PARAMS (integer, read-only)

The number of parameters (placeholders) in the prepared statement. See SUBSTITUTION VARIABLES below for more details.

準備(prepare)されたSQL文のパラメータ(プレースホルダ)の数。 詳細については下記の置換変数をご覧ください。

NAME (array-ref, read-only)

Returns a reference to an array of field names for each column. The names may contain spaces but should not be truncated or have any trailing space. Note that the names have the letter case (upper, lower or mixed) as returned by the driver being used. Portable applications should use "NAME_lc" or "NAME_uc".

各カラムに対応するフィールド名の配列へのリファレンスを返します。 名前には空白が入っているかもしれませんが、切り捨てられることはありませんし、 後ろの空白を持ちます。 返されるときの文字の大文字、小文字、その混合は使われている データベースによるということに注意してください。 移植性の高いアプリーケーションは "NAME_lc" または "NAME_uc" を使うべきです。

  print "First column name: $sth->{NAME}->[0]\n";

Also note that the name returned for (aggregate) functions like count(*) or max(c_foo) is determined by the database server and not by DBI or the DBD backend.

Also note that the name returned for (aggregate) functions like count(*) or max(c_foo) is determined by the database server and not by DBI or the DBD backend. (TBT)

NAME_lc (array-ref, read-only)

Like "NAME" but always returns lowercase names.

"NAME" と同様ですが常に小文字で名前が返されます。

NAME_uc (array-ref, read-only)

Like "NAME" but always returns uppercase names.

"NAME" と同様ですが常に大文字で名前が返されます。

NAME_hash (hash-ref, read-only)

NAME_lc_hash (hash-ref, read-only)

NAME_uc_hash (hash-ref, read-only)

The NAME_hash, NAME_lc_hash, and NAME_uc_hash attributes return column name information as a reference to a hash.

The NAME_hash, NAME_lc_hash, and NAME_uc_hash attributes return column name information as a reference to a hash. (TBT)

The keys of the hash are the names of the columns. The letter case of the keys corresponds to the letter case returned by the NAME, NAME_lc, and NAME_uc attributes respectively (as described above).

The keys of the hash are the names of the columns. The letter case of the keys corresponds to the letter case returned by the NAME, NAME_lc, and NAME_uc attributes respectively (as described above). (TBT)

The value of each hash entry is the perl index number of the corresponding column (counting from 0). For example:

The value of each hash entry is the perl index number of the corresponding column (counting from 0). For example: (TBT)

  $sth = $dbh->prepare("select Id, Name from table");
  $sth->execute;
  @row = $sth->fetchrow_array;
  print "Name $row[ $sth->{NAME_lc_hash}{name} ]\n";

TYPE (array-ref, read-only)

Returns a reference to an array of integer values for each column. The value indicates the data type of the corresponding column.

各カラムに対応する整数値の配列へのリファレンスを返します。 値は対応するカラムのデータ型を示します。

The values correspond to the international standards (ANSI X3.135 and ISO/IEC 9075) which, in general terms, means ODBC. Driver-specific types that don't exactly match standard types should generally return the same values as an ODBC driver supplied by the makers of the database. That might include private type numbers in ranges the vendor has officially registered with the ISO working group:

この値は国際規約(ANSI X3.135 と ISO/IEC 9075)(一般には ODBC を意味します)に 対応しています。 標準の型に正確にあてはまらない、ドライバ特有の型では、通常、データベースの メーカーが提供する ODBC ドライバと同じ値を返さなければいけません。 これはベンダーが公式に ISO ワーキンググループに予約しているプライベートな 型番号を含みます。:

  ftp://sqlstandards.org/SC32/SQL_Registry/

Where there's no vendor-supplied ODBC driver to be compatible with, the DBI driver can use type numbers in the range that is now officially reserved for use by the DBI: -9999 to -9000.

DBI ドライバは互換性を持つ ODBC ドライバを提供されているベンダーがなければ、 DBI が使用するために公式に予約されている -9999 から -9000 の範囲の型番号を 使うことができます。

All possible values for TYPE should have at least one entry in the output of the type_info_all method (see "type_info_all").

TYPE がとりうるすべての値は、type_info_all メソッドの出力のなかの、 少なくとも一つの要素として入っていなければなりません (type_info_all をご覧下さい)。

PRECISION (array-ref, read-only)

Returns a reference to an array of integer values for each column.

各カラムに対応する整数値の配列へのリファレンスを返します。

For numeric columns, the value is the maximum number of digits (without considering a sign character or decimal point). Note that the "display size" for floating point types (REAL, FLOAT, DOUBLE) can be up to 7 characters greater than the precision (for the sign + decimal point + the letter E + a sign + 2 or 3 digits).

数値のカラムでは、値は数値の最大桁数です (符号文字や小数点を除きます)。 浮動小数点の型(REAL, FLOAT, DOUBLE)では「表示サイズ」は precision よりも 7 文字までは、大きいかもしれません (符号 + 小数点 + E という文字 + 符号 +2 または 3 桁)。

For any character type column the value is the OCTET_LENGTH, in other words the number of bytes, not characters.

For any character type column the value is the OCTET_LENGTH, in other words the number of bytes, not characters. (TBT)

(More recent standards refer to this as COLUMN_SIZE but we stick with PRECISION for backwards compatibility.)

(More recent standards refer to this as COLUMN_SIZE but we stick with PRECISION for backwards compatibility.) (TBT)

SCALE (array-ref, read-only)

Returns a reference to an array of integer values for each column. NULL (undef) values indicate columns where scale is not applicable.

各カラムに対応する整数値の配列へのリファレンスを返します。 NULL (undef) 値には、scale が適用されないことを示します。

NULLABLE (array-ref, read-only)

Returns a reference to an array indicating the possibility of each column returning a null. Possible values are 0 (or an empty string) = no, 1 = yes, 2 = unknown.

各カラムが NULL にしていいかどうかを示す値を配列へのリファレンスを返します。 とりうる値は、0 (または空文字列)= 受け入れない、1 = 受け入れる、 2 = 不明です。

  print "First column may return NULL\n" if $sth->{NULLABLE}->[0];

CursorName (string, read-only)

Returns the name of the cursor associated with the statement handle, if available. If not available or if the database driver does not support the "where current of ..." SQL syntax, then it returns undef.

文ハンドルが使えるのであれば、文ハンドルに 結び付けられたカーソル名を返します。 使えないか、"where current of ..." SQL の書き方をデータベースドライバが サポートしていなければ undef を返します。

Database (dbh, read-only)

Returns the parent $dbh of the statement handle.

文ハンドルの親 $dbh を返します。

Statement (string, read-only)

Returns the statement string passed to the "prepare" method.

"prepare" メソッドに渡された、文文字列を返します。

ParamValues (hash ref, read-only)

Returns a reference to a hash containing the values currently bound to placeholders. The keys of the hash are the 'names' of the placeholders, typically integers starting at 1. Returns undef if not supported by the driver.

Returns a reference to a hash containing the values currently bound to placeholders. The keys of the hash are the 'names' of the placeholders, typically integers starting at 1. Returns undef if not supported by the driver. (TBT)

See "ShowErrorStatement" for an example of how this is used.

これの使い方に関する例については "ShowErrorStatement" を参照してください。

* Keys:

* キー:

If the driver supports ParamValues but no values have been bound yet then the driver should return a hash with placeholders names in the keys but all the values undef, but some drivers may return a ref to an empty hash because they can't pre-determine the names.

If the driver supports ParamValues but no values have been bound yet then the driver should return a hash with placeholders names in the keys but all the values undef, but some drivers may return a ref to an empty hash because they can't pre-determine the names. (TBT)

It is possible that the keys in the hash returned by ParamValues are not exactly the same as those implied by the prepared statement. For example, DBD::Oracle translates '?' placeholders into ':pN' where N is a sequence number starting at 1.

It is possible that the keys in the hash returned by ParamValues are not exactly the same as those implied by the prepared statement. For example, DBD::Oracle translates '?' placeholders into ':pN' where N is a sequence number starting at 1. (TBT)

* Values:

* 値:

It is possible that the values in the hash returned by ParamValues are not exactly the same as those passed to bind_param() or execute(). The driver may have slightly modified values in some way based on the TYPE the value was bound with. For example a floating point value bound as an SQL_INTEGER type may be returned as an integer. The values returned by ParamValues can be passed to another bind_param() method with the same TYPE and will be seen by the database as the same value. See also "ParamTypes" below.

It is possible that the values in the hash returned by ParamValues are not exactly the same as those passed to bind_param() or execute(). The driver may have slightly modified values in some way based on the TYPE the value was bound with. For example a floating point value bound as an SQL_INTEGER type may be returned as an integer. The values returned by ParamValues can be passed to another bind_param() method with the same TYPE and will be seen by the database as the same value. See also "ParamTypes" below. (TBT)

The ParamValues attribute was added in DBI 1.28.

ParamValues 属性は DBI 1.28 で追加されました。

ParamTypes (hash ref, read-only)

Returns a reference to a hash containing the type information currently bound to placeholders. Returns undef if not supported by the driver.

Returns a reference to a hash containing the type information currently bound to placeholders. Returns undef if not supported by the driver. (TBT)

* Keys:

* キー:

See "ParamValues" above.

上述の "ParamValues" を参照してください。

* Values:

* 値:

The hash values are hashrefs of type information in the same form as that passed to the various bind_param() methods (See "bind_param" for the format and values).

The hash values are hashrefs of type information in the same form as that passed to the various bind_param() methods (See "bind_param" for the format and values). (TBT)

It is possible that the values in the hash returned by ParamTypes are not exactly the same as those passed to bind_param() or execute(). Param attributes specified using the abbreviated form, like this:

It is possible that the values in the hash returned by ParamTypes are not exactly the same as those passed to bind_param() or execute(). Param attributes specified using the abbreviated form, like this: (TBT)

    $sth->bind_param(1, SQL_INTEGER);

are returned in the expanded form, as if called like this:

は、以下のように呼び出されたかのように拡張形式で返されます:

    $sth->bind_param(1, { TYPE => SQL_INTEGER });

The driver may have modified the type information in some way based on the bound values, other hints provided by the prepare()'d SQL statement, or alternate type mappings required by the driver or target database system. The driver may also add private keys (with names beginning with the drivers reserved prefix, e.g., odbc_xxx).

The driver may have modified the type information in some way based on the bound values, other hints provided by the prepare()'d SQL statement, or alternate type mappings required by the driver or target database system. The driver may also add private keys (with names beginning with the drivers reserved prefix, e.g., odbc_xxx). (TBT)

* Example:

* 例:

The keys and values in the returned hash can be passed to the various bind_param() methods to effectively reproduce a previous param binding. For example:

The keys and values in the returned hash can be passed to the various bind_param() methods to effectively reproduce a previous param binding. For example: (TBT)

  # assuming $sth1 is a previously prepared statement handle
  my $sth2 = $dbh->prepare( $sth1->{Statement} );
  my $ParamValues = $sth1->{ParamValues} || {};
  my $ParamTypes  = $sth1->{ParamTypes}  || {};
  $sth2->bind_param($_, $PV->{$_} $PT->{$_})
    for keys %{ %$PV, %$PT };
  $sth2->execute();

The ParamTypes attribute was added in DBI 1.49. Implementation is the responsibility of individual drivers; the DBI layer default implementation simply returns undef.

The ParamTypes attribute was added in DBI 1.49. Implementation is the responsibility of individual drivers; the DBI layer default implementation simply returns undef. (TBT)

ParamArrays (hash ref, read-only)

Returns a reference to a hash containing the values currently bound to placeholders with "execute_array" or "bind_param_array". The keys of the hash are the 'names' of the placeholders, typically integers starting at 1. Returns undef if not supported by the driver or no arrays of parameters are bound.

Returns a reference to a hash containing the values currently bound to placeholders with "execute_array" or "bind_param_array". The keys of the hash are the 'names' of the placeholders, typically integers starting at 1. Returns undef if not supported by the driver or no arrays of parameters are bound. (TBT)

Each key value is an array reference containing a list of the bound parameters for that column.

Each key value is an array reference containing a list of the bound parameters for that column. (TBT)

For example:

例えば:

  $sth = $dbh->prepare("INSERT INTO staff (id, name) values (?,?)");
  $sth->execute_array({},[1,2], ['fred','dave']);
  if ($sth->{ParamArrays}) {
      foreach $param (keys %{$sth->{ParamArrays}}) {
          printf "Parameters for %s : %s\n", $param,
          join(",", @{$sth->{ParamArrays}->{$param}});
      }
  }

It is possible that the values in the hash returned by ParamArrays are not exactly the same as those passed to "bind_param_array" or "execute_array". The driver may have slightly modified values in some way based on the TYPE the value was bound with. For example a floating point value bound as an SQL_INTEGER type may be returned as an integer.

It is possible that the values in the hash returned by ParamArrays are not exactly the same as those passed to "bind_param_array" or "execute_array". The driver may have slightly modified values in some way based on the TYPE the value was bound with. For example a floating point value bound as an SQL_INTEGER type may be returned as an integer. (TBT)

It is also possible that the keys in the hash returned by ParamArrays are not exactly the same as those implied by the prepared statement. For example, DBD::Oracle translates '?' placeholders into ':pN' where N is a sequence number starting at 1.

It is also possible that the keys in the hash returned by ParamArrays are not exactly the same as those implied by the prepared statement. For example, DBD::Oracle translates '?' placeholders into ':pN' where N is a sequence number starting at 1. (TBT)

RowsInCache (integer, read-only)

If the driver supports a local row cache for SELECT statements, then this attribute holds the number of un-fetched rows in the cache. If the driver doesn't, then it returns undef. Note that some drivers pre-fetch rows on execute, whereas others wait till the first fetch.

ドライバが SELECT 文についてローカルな行キャッシュを サポートしていれば、この属性はキャシュのなかで fetch されていない行数を 返します。 ドライバがサポートしていなければ、undef を返します。 ドライバによっては execute 時点で前もって取り出すものもありますし、最初の fetch が来るまで待つものもあります。

See also the "RowCacheSize" database handle attribute.

データベースハンドル属性 "RowCacheSize" もご覧ください。

さらなる情報

カタログメソッド

An application can retrieve metadata information from the DBMS by issuing appropriate queries on the views of the Information Schema. Unfortunately, INFORMATION_SCHEMA views are seldom supported by the DBMS. Special methods (catalog methods) are available to return result sets for a small but important portion of that metadata:

An application can retrieve metadata information from the DBMS by issuing appropriate queries on the views of the Information Schema. Unfortunately, INFORMATION_SCHEMA views are seldom supported by the DBMS. Special methods (catalog methods) are available to return result sets for a small but important portion of that metadata: (TBT)

  column_info
  foreign_key_info
  primary_key_info
  table_info
  statistics_info

All catalog methods accept arguments in order to restrict the result sets. Passing undef to an optional argument does not constrain the search for that argument. However, an empty string ('') is treated as a regular search criteria and will only match an empty value.

All catalog methods accept arguments in order to restrict the result sets. Passing undef to an optional argument does not constrain the search for that argument. However, an empty string ('') is treated as a regular search criteria and will only match an empty value. (TBT)

Note: SQL/CLI and ODBC differ in the handling of empty strings. An empty string will not restrict the result set in SQL/CLI.

Note: SQL/CLI and ODBC differ in the handling of empty strings. An empty string will not restrict the result set in SQL/CLI. (TBT)

Most arguments in the catalog methods accept only ordinary values, e.g. the arguments of primary_key_info(). Such arguments are treated as a literal string, i.e. the case is significant and quote characters are taken literally.

Most arguments in the catalog methods accept only ordinary values, e.g. the arguments of primary_key_info(). Such arguments are treated as a literal string, i.e. the case is significant and quote characters are taken literally. (TBT)

Some arguments in the catalog methods accept search patterns (strings containing '_' and/or '%'), e.g. the $table argument of column_info(). Passing '%' is equivalent to leaving the argument undef.

Some arguments in the catalog methods accept search patterns (strings containing '_' and/or '%'), e.g. the $table argument of column_info(). Passing '%' is equivalent to leaving the argument undef. (TBT)

Caveat: The underscore ('_') is valid and often used in SQL identifiers. Passing such a value to a search pattern argument may return more rows than expected! To include pattern characters as literals, they must be preceded by an escape character which can be achieved with

Caveat: The underscore ('_') is valid and often used in SQL identifiers. Passing such a value to a search pattern argument may return more rows than expected! To include pattern characters as literals, they must be preceded by an escape character which can be achieved with (TBT)

  $esc = $dbh->get_info( 14 );  # SQL_SEARCH_PATTERN_ESCAPE
  $search_pattern =~ s/([_%])/$esc$1/g;

The ODBC and SQL/CLI specifications define a way to change the default behaviour described above: All arguments (except list value arguments) are treated as identifier if the SQL_ATTR_METADATA_ID attribute is set to SQL_TRUE. Quoted identifiers are very similar to ordinary values, i.e. their body (the string within the quotes) is interpreted literally. Unquoted identifiers are compared in UPPERCASE.

The ODBC and SQL/CLI specifications define a way to change the default behaviour described above: All arguments (except list value arguments) are treated as identifier if the SQL_ATTR_METADATA_ID attribute is set to SQL_TRUE. Quoted identifiers are very similar to ordinary values, i.e. their body (the string within the quotes) is interpreted literally. Unquoted identifiers are compared in UPPERCASE. (TBT)

The DBI (currently) does not support the SQL_ATTR_METADATA_ID attribute, i.e. it behaves like an ODBC driver where SQL_ATTR_METADATA_ID is set to SQL_FALSE.

The DBI (currently) does not support the SQL_ATTR_METADATA_ID attribute, i.e. it behaves like an ODBC driver where SQL_ATTR_METADATA_ID is set to SQL_FALSE. (TBT)

トランザクション

Transactions are a fundamental part of any robust database system. They protect against errors and database corruption by ensuring that sets of related changes to the database take place in atomic (indivisible, all-or-nothing) units.

トランザクションはすべての堅牢なデータベースシステムの基本的な部分です。 データベースへの関連する一連の変更が、アトミックな(独立していて オールオアナッシングな)単位で行われること保証することにより、エラーと データベース障害から守ります。

This section applies to databases that support transactions and where AutoCommit is off. See "AutoCommit" for details of using AutoCommit with various types of databases.

この節はトランザクションをサポートし、AutoCommit がオフに なっているデータベースにあてはまります。 各種のデータベースに対する AutoCommit の使い方の詳細については "AutoCommit" をご覧ください。

The recommended way to implement robust transactions in Perl applications is to use RaiseError and eval { ... } (which is very fast, unlike eval "..."). For example:

Perl アプリケーションで堅牢なトランザクションを実現するためのお勧めの方法は、 RaiseErroreval { ... } を使うことです (これは eval "..." と違ってとても速く動作します)。 例えば:

  $dbh->{AutoCommit} = 0;  # enable transactions, if possible
  $dbh->{RaiseError} = 1;
  eval {
      foo(...)        # do lots of work here
      bar(...)        # including inserts
      baz(...)        # and updates
      $dbh->commit;   # commit the changes if we get this far
  };
  if ($@) {
      warn "Transaction aborted because $@";
      # now rollback to undo the incomplete changes
      # but do it in an eval{} as it may also fail
      eval { $dbh->rollback };
      # add other application on-error-clean-up code here
  }
  $dbh->{AutoCommit} = 0;  # 可能であれば、トランザクションを有効にします
  $dbh->{RaiseError} = 1;
  eval {
      foo(...)        # INSERT や UPDATE を含む
      bar(...)        # 多くの処理を
      baz(...)        # ここでします
      $dbh->commit;   # ここまで来たらコミットします
  };
  if ($@) {
      warn "Transaction aborted because $@";
      # ここで不完全な変更を元に戻すためにロールバックします
      # しかしこれも失敗することがあるので eval{} の中で行います
      eval { $dbh->rollback };
      # 他のアプリケーションの後片付けの処理をここに入れます
  }

If the RaiseError attribute is not set, then DBI calls would need to be manually checked for errors, typically like this:

RaiseError 属性が設定されていなければ、DBI 呼び出しは手動でエラーの チェックをする必要があります。 通常は以下のようにします:

  $h->method(@args) or die $h->errstr;

With RaiseError set, the DBI will automatically die if any DBI method call on that handle (or a child handle) fails, so you don't have to test the return value of each method call. See "RaiseError" for more details.

RaiseError を設定すると、そのハンドル(またはその子供のハンドル)で 呼び出される DBI メソッドが失敗すると、DBI は自動的に die します。 そのため各メソッド呼び出しの戻り値をいちいちチェックする必要が なくなります。 詳細については "RaiseError" をご覧ください。

A major advantage of the eval approach is that the transaction will be properly rolled back if any code (not just DBI calls) in the inner application dies for any reason. The major advantage of using the $h->{RaiseError} attribute is that all DBI calls will be checked automatically. Both techniques are strongly recommended.

eval による方法の大きな利点は、アプリケーション内部のいかなる理由で、 (DBI呼び出しに限らず)どのような処理で die しても、トランザクションが 適切にロールバックされることにあります。 $h->{RaiseError} 属性を使う大きな利点は、すべての DBI 呼び出しが自動的に チェックされることにあります。 どちらのテクニックも強くお勧めします。

After calling commit or rollback many drivers will not let you fetch from a previously active SELECT statement handle that's a child of the same database handle. A typical way round this is to connect the the database twice and use one connection for SELECT statements.

commitrollback を呼び出した後、多くのドライバは同じ データベースハンドルの子供で以前はアクティブだった SELECT 文ハンドルからの取り出しをさせてくれません。 これを避ける典型的な方法は、データベースに 2 回接続し、一つの接続を SELECT 文のために使うことです。

See "AutoCommit" and "disconnect" for other important information about transactions.

トランザクションに関するその他の重要な情報については "AutoCommit""disconnect" を参照してください。

BLOB / LONG / Memoフィールドを扱う

Many databases support "blob" (binary large objects), "long", or similar datatypes for holding very long strings or large amounts of binary data in a single field. Some databases support variable length long values over 2,000,000,000 bytes in length.

多くのデータベースは一つのフィールドにとても長い文字列や、巨大な バイナリデータを保持するために、"blob" (binary large objects=巨大なバイナリ オブジェクト), "long" または同じようなデータ型をサポートしています。 データベースによっては、2,000,000,000 バイトを越えるような長さの可変長の値も サポートしています。

Since values of that size can't usually be held in memory, and because databases can't usually know in advance the length of the longest long that will be returned from a SELECT statement (unlike other data types), some special handling is required.

その大きさの値を通常メモリに保持することができないこと、(他のデータ型と 違って)SELECT 文によって返される最大長をデータベースは 前もってわからないことから、特別な操作が必要になります。

In this situation, the value of the $h->{LongReadLen} attribute is used to determine how much buffer space to allocate when fetching such fields. The $h->{LongTruncOk} attribute is used to determine how to behave if a fetched value can't fit into the buffer.

このような場合に、そのようなフィールドを取り出すときに、どれくらいの バッファスペースを確保するかを決めるために、$h->{LongReadLen} 属性の 値が使われます。 $h->{LongTruncOk} 属性は、取り出した値がバッファに 入りきらなかったときにどのように振る舞うかを決定するのに使われます。

See the description of "LongReadLen" for more information.

さらなる情報については "LongReadLen" の記述を参照してください。

When trying to insert long or binary values, placeholders should be used since there are often limits on the maximum size of an INSERT statement and the "quote" method generally can't cope with binary data. See "Placeholders and Bind Values".

長い値やバイナリの値を挿入するとき、INSERT 文の大きさには よく限度があり、"quote" メソッドは通常バイナリデータに対処できないので、 プレースホルダを使わなければなりません。 "Placeholders and Bind Values" をご覧ください。

簡単な例

Here's a complete example program to select and fetch some data:

データをいくつか選択(select)し、取り出す(fetch)一通り揃ったプログラム例を 以下に示します:

  my $data_source = "dbi::DriverName:db_name";
  my $dbh = DBI->connect($data_source, $user, $password)
      or die "Can't connect to $data_source: $DBI::errstr";

  my $sth = $dbh->prepare( q{
          SELECT name, phone
          FROM mytelbook
  }) or die "Can't prepare statement: $DBI::errstr";

  my $rc = $sth->execute
      or die "Can't execute statement: $DBI::errstr";

  print "Query will return $sth->{NUM_OF_FIELDS} fields.\n\n";
  print "Field names: @{ $sth->{NAME} }\n";

  while (($name, $phone) = $sth->fetchrow_array) {
      print "$name: $phone\n";
  }
  # check for problems which may have terminated the fetch early
  die $sth->errstr if $sth->err;

  $dbh->disconnect;

Here's a complete example program to insert some data from a file. (This example uses RaiseError to avoid needing to check each call).

ファイルからデータを挿入する一通り揃ったプログラム例を以下に示します。 (この例では各呼び出しでチェックする必要をなくすために、RaiseError を 使っています)。

  my $dbh = DBI->connect("dbi:DriverName:db_name", $user, $password, {
      RaiseError => 1, AutoCommit => 0
  });

  my $sth = $dbh->prepare( q{
      INSERT INTO table (name, phone) VALUES (?, ?)
  });

  open FH, "<phone.csv" or die "Unable to open phone.csv: $!";
  while (<FH>) {
      chomp;
      my ($name, $phone) = split /,/;
      $sth->execute($name, $phone);
  }
  close FH;

  $dbh->commit;
  $dbh->disconnect;

Here's how to convert fetched NULLs (undefined values) into empty strings:

これは取り出した NULL(未定義値)を空文字列に変換する方法です:

  while($row = $sth->fetchrow_arrayref) {
    # this is a fast and simple way to deal with nulls:
    foreach (@$row) { $_ = '' unless defined }
    print "@$row\n";
  }

The q{...} style quoting used in these examples avoids clashing with quotes that may be used in the SQL statement. Use the double-quote like qq{...} operator if you want to interpolate variables into the string. See "Quote and Quote-like Operators" in perlop for more details.

SQL文で使われているかもしれないクォートの対応が壊れないように、 これら例では q{...} 形式のクォートを使っています。 文字列中の変数を解釈して欲しいときには、qq{...} 演算子のような ダブル・クォートを使ってください。 詳細は "Quote and Quote-like Operators" in perlop をご覧ください。

スレッドとスレッドセーフ性

Perl 5.7 and later support a new threading model called iThreads. (The old "5.005 style" threads are not supported by the DBI.)

Perl 5.7 and later support a new threading model called iThreads. (The old "5.005 style" threads are not supported by the DBI.) (TBT)

In the iThreads model each thread has it's own copy of the perl interpreter. When a new thread is created the original perl interpreter is 'cloned' to create a new copy for the new thread.

In the iThreads model each thread has it's own copy of the perl interpreter. When a new thread is created the original perl interpreter is 'cloned' to create a new copy for the new thread. (TBT)

If the DBI and drivers are loaded and handles created before the thread is created then it will get a cloned copy of the DBI, the drivers and the handles.

If the DBI and drivers are loaded and handles created before the thread is created then it will get a cloned copy of the DBI, the drivers and the handles. (TBT)

However, the internal pointer data within the handles will refer to the DBI and drivers in the original interpreter. Using those handles in the new interpreter thread is not safe, so the DBI detects this and croaks on any method call using handles that don't belong to the current thread (except for DESTROY).

However, the internal pointer data within the handles will refer to the DBI and drivers in the original interpreter. Using those handles in the new interpreter thread is not safe, so the DBI detects this and croaks on any method call using handles that don't belong to the current thread (except for DESTROY). (TBT)

Because of this (possibly temporary) restriction, newly created threads must make their own connections to the database. Handles can't be shared across threads.

Because of this (possibly temporary) restriction, newly created threads must make their own connections to the database. Handles can't be shared across threads. (TBT)

But BEWARE, some underlying database APIs (the code the DBD driver uses to talk to the database, often supplied by the database vendor) are not thread safe. If it's not thread safe, then allowing more than one thread to enter the code at the same time may cause subtle/serious problems. In some cases allowing more than one thread to enter the code, even if not at the same time, can cause problems. You have been warned.

But BEWARE, some underlying database APIs (the code the DBD driver uses to talk to the database, often supplied by the database vendor) are not thread safe. If it's not thread safe, then allowing more than one thread to enter the code at the same time may cause subtle/serious problems. In some cases allowing more than one thread to enter the code, even if not at the same time, can cause problems. You have been warned. (TBT)

Using DBI with perl threads is not yet recommended for production environments. For more information see http://www.perlmonks.org/index.pl?node_id=288022

Using DBI with perl threads is not yet recommended for production environments. For more information see http://www.perlmonks.org/index.pl?node_id=288022 (TBT)

Note: There is a bug in perl 5.8.2 when configured with threads and debugging enabled (bug #24463) which causes a DBI test to fail.

Note: There is a bug in perl 5.8.2 when configured with threads and debugging enabled (bug #24463) which causes a DBI test to fail. (TBT)

シグナルの扱いとキャンセル操作

[The following only applies to systems with unix-like signal handling. I'd welcome additions for other systems, especially Windows.]

[The following only applies to systems with unix-like signal handling. I'd welcome additions for other systems, especially Windows.] (TBT)

The first thing to say is that signal handling in Perl versions less than 5.8 is not safe. There is always a small risk of Perl crashing and/or core dumping when, or after, handling a signal because the signal could arrive and be handled while internal data structures are being changed. If the signal handling code used those same internal data structures it could cause all manner of subtle and not-so-subtle problems. The risk was reduced with 5.4.4 but was still present in all perls up through 5.8.0.

まず最初にいうべきことは、Perl バージョン 5.8 以前でのシグナル操作は 安全ではない ということです。 シグナルを扱ったときまたは後に、Perlがクラッシュする、またははコアダンプを おこす危険性がまだ若干あります; because the signal could arrive and be handled while internal data structures are being changed. If the signal handling code used those same internal data structures it could cause all manner of subtle and not-so-subtle problems. The risk was reduced with 5.4.4 but was still present in all perls up through 5.8.0. (TBT)

Beginning in perl 5.8.0 perl implements 'safe' signal handling if your system has the POSIX sigaction() routine. Now when a signal is delivered perl just makes a note of it but does not run the %SIG handler. The handling is 'deferred' until a 'safe' moment.

Beginning in perl 5.8.0 perl implements 'safe' signal handling if your system has the POSIX sigaction() routine. Now when a signal is delivered perl just makes a note of it but does not run the %SIG handler. The handling is 'deferred' until a 'safe' moment. (TBT)

Although this change made signal handling safe, it also lead to a problem with signals being deferred for longer than you'd like. If a signal arrived while executing a system call, such as waiting for data on a network connection, the signal is noted and then the system call that was executing returns with an EINTR error code to indicate that it was interrupted. All fine so far.

Although this change made signal handling safe, it also lead to a problem with signals being deferred for longer than you'd like. If a signal arrived while executing a system call, such as waiting for data on a network connection, the signal is noted and then the system call that was executing returns with an EINTR error code to indicate that it was interrupted. All fine so far. (TBT)

The problem comes when the code that made the system call sees the EINTR code and decides it's going to call it again. Perl doesn't do that, but database code sometimes does. If that happens then the signal handler doesn't get called until later. Maybe much later.

The problem comes when the code that made the system call sees the EINTR code and decides it's going to call it again. Perl doesn't do that, but database code sometimes does. If that happens then the signal handler doesn't get called until later. Maybe much later. (TBT)

Fortunately there are ways around this which we'll discuss below. Unfortunately they make signals unsafe again.

Fortunately there are ways around this which we'll discuss below. Unfortunately they make signals unsafe again. (TBT)

The two most common uses of signals in relation to the DBI are for canceling operations when the user types Ctrl-C (interrupt), and for implementing a timeout using alarm() and $SIG{ALRM}.

DBI に関連して最も一般的に使われるシグナルの二つは、Ctrl-C(中断)を 押したときのキャンセル操作と、alarm()$SIG{ALRM} を使って実現される タイムアウトです。

Cancel

(キャンセル)

The DBI provides a cancel method for statement handles. The cancel method should abort the current operation and is designed to be called from a signal handler. For example:

DBI は cancel メソッドを文ハンドルに用意しています。 cancel メソッドはその時点の操作を中断させなければいけません; そしてシグナルハンドラから呼ばれるように設計されています。 例えば:

  $SIG{INT} = sub { $sth->cancel };

However, few drivers implement this (the DBI provides a default method that just returns undef) and, even if implemented, there is still a possibility that the statement handle, and even the parent database handle, will not be usable afterwards.

しかし、これを実装しているドライバはほとんどなく(DBI は undef を 返すだけのデフォルトのメソッドを提供しています)、たとえ 実装されていたとしても、文ハンドル、さらに場合によっては 親のデータベースハンドルが、それ以降、使えなくなる可能性があります。

If cancel returns true, then it has successfully invoked the database engine's own cancel function. If it returns false, then cancel failed. If it returns undef, then the database driver does not have cancel implemented - very few do.

cancel が真を返せば、それはデータベースエンジンそのものの キャンセル機能を呼び出すことに成功しています。 偽を返せば、cancel は失敗しています。 undef を返せば、データベースエンジンはキャンセルを実装していません - めったにありませんが。

Timeout

(タイムアウト)

The traditional way to implement a timeout is to set $SIG{ALRM} to refer to some code that will be executed when an ALRM signal arrives and then to call alarm($seconds) to schedule an ALRM signal to be delivered $seconds in the future. For example:

The traditional way to implement a timeout is to set $SIG{ALRM} to refer to some code that will be executed when an ALRM signal arrives and then to call alarm($seconds) to schedule an ALRM signal to be delivered $seconds in the future. For example: (TBT)

  eval {
    local $SIG{ALRM} = sub { die "TIMEOUT\n" }; # N.B. \n required
    eval {
      alarm($seconds);
      ... code to execute with timeout here (which may die) ...
    };
    # outer eval catches alarm that might fire JUST before this alarm(0)
    alarm(0);  # cancel alarm (if code ran fast)
    die "$@" if $@;
  };
  if ( $@ eq "TIMEOUT\n" ) { ... }
  elsif ($@) { ... } # some other error

The first (outer) eval is used to avoid the unlikely but possible chance that the "code to execute" dies and the alarm fires before it is cancelled. Without the outer eval, if this happened your program will die if you have no ALRM handler or a non-local alarm handler will be called.

The first (outer) eval is used to avoid the unlikely but possible chance that the "code to execute" dies and the alarm fires before it is cancelled. Without the outer eval, if this happened your program will die if you have no ALRM handler or a non-local alarm handler will be called. (TBT)

Unfortunately, as described above, this won't always work as expected, depending on your perl version and the underlying database code.

Unfortunately, as described above, this won't always work as expected, depending on your perl version and the underlying database code. (TBT)

With Oracle for instance (DBD::Oracle), if the system which hosts the database is down the DBI->connect() call will hang for several minutes before returning an error.

With Oracle for instance (DBD::Oracle), if the system which hosts the database is down the DBI->connect() call will hang for several minutes before returning an error. (TBT)

The solution on these systems is to use the POSIX::sigaction() routine to gain low level access to how the signal handler is installed.

The solution on these systems is to use the POSIX::sigaction() routine to gain low level access to how the signal handler is installed. (TBT)

The code would look something like this (for the DBD-Oracle connect()):

コードは以下のような感じになります (DBD-Oracle connect() の場合):

   use POSIX qw(:signal_h);

   my $mask = POSIX::SigSet->new( SIGALRM ); # signals to mask in the handler
   my $action = POSIX::SigAction->new(
       sub { die "connect timeout\n" },        # the handler code ref
       $mask,
       # not using (perl 5.8.2 and later) 'safe' switch or sa_flags
   );
   my $oldaction = POSIX::SigAction->new();
   sigaction( SIGALRM, $action, $oldaction );
   my $dbh;
   eval {
      eval {
        alarm(5); # seconds before time out
        $dbh = DBI->connect("dbi:Oracle:$dsn" ... );
      };
      alarm(0); # cancel alarm (if connect worked fast)
      die "$@\n" if $@; # connect died
   };
   sigaction( SIGALRM, $oldaction );  # restore original signal handler
   if ( $@ ) {
     if ($@ eq "connect timeout\n") {...}
     else { # connect died }
   }

See previous example for the reasoning around the double eval.

2 重 eval の意味については前述の例を参照してください。

Similar techniques can be used for canceling statement execution.

同様のテクニックは文の実行のキャンセルにも使えます。

Unfortunately, this solution is somewhat messy, and it does not work with perl versions less than perl 5.8 where POSIX::sigaction() appears to be broken.

Unfortunately, this solution is somewhat messy, and it does not work with perl versions less than perl 5.8 where POSIX::sigaction() appears to be broken. (TBT)

For a cleaner implementation that works across perl versions, see Lincoln Baxter's Sys::SigAction module at http://search.cpan.org/~lbaxter/Sys-SigAction/. The documentation for Sys::SigAction includes an longer discussion of this problem, and a DBD::Oracle test script.

For a cleaner implementation that works across perl versions, see Lincoln Baxter's Sys::SigAction module at http://search.cpan.org/~lbaxter/Sys-SigAction/. The documentation for Sys::SigAction includes an longer discussion of this problem, and a DBD::Oracle test script. (TBT)

Be sure to read all the signal handling sections of the perlipc manual.

perlipc マニュアルのシグナルハンドリングの章を全て読むようにしてください。

And finally, two more points to keep firmly in mind. Firstly, remember that what we've done here is essentially revert to old style unsafe handling of these signals. So do as little as possible in the handler. Ideally just die(). Secondly, the handles in use at the time the signal is handled may not be safe to use afterwards.

And finally, two more points to keep firmly in mind. Firstly, remember that what we've done here is essentially revert to old style unsafe handling of these signals. So do as little as possible in the handler. Ideally just die(). Secondly, the handles in use at the time the signal is handled may not be safe to use afterwards. (TBT)

DBI のサブクラス化

DBI can be subclassed and extended just like any other object oriented module. Before we talk about how to do that, it's important to be clear about the various DBI classes and how they work together.

DBI can be subclassed and extended just like any other object oriented module. Before we talk about how to do that, it's important to be clear about the various DBI classes and how they work together. (TBT)

By default $dbh = DBI->connect(...) returns a $dbh blessed into the DBI::db class. And the $dbh->prepare method returns an $sth blessed into the DBI::st class (actually it simply changes the last four characters of the calling handle class to be ::st).

By default $dbh = DBI->connect(...) returns a $dbh blessed into the DBI::db class. And the $dbh->prepare method returns an $sth blessed into the DBI::st class (actually it simply changes the last four characters of the calling handle class to be ::st). (TBT)

The leading 'DBI' is known as the 'root class' and the extra '::db' or '::st' are the 'handle type suffixes'. If you want to subclass the DBI you'll need to put your overriding methods into the appropriate classes. For example, if you want to use a root class of MySubDBI and override the do(), prepare() and execute() methods, then your do() and prepare() methods should be in the MySubDBI::db class and the execute() method should be in the MySubDBI::st class.

The leading 'DBI' is known as the 'root class' and the extra '::db' or '::st' are the 'handle type suffixes'. If you want to subclass the DBI you'll need to put your overriding methods into the appropriate classes. For example, if you want to use a root class of MySubDBI and override the do(), prepare() and execute() methods, then your do() and prepare() methods should be in the MySubDBI::db class and the execute() method should be in the MySubDBI::st class. (TBT)

To setup the inheritance hierarchy the @ISA variable in MySubDBI::db should include DBI::db and the @ISA variable in MySubDBI::st should include DBI::st. The MySubDBI root class itself isn't currently used for anything visible and so, apart from setting @ISA to include DBI, it can be left empty.

To setup the inheritance hierarchy the @ISA variable in MySubDBI::db should include DBI::db and the @ISA variable in MySubDBI::st should include DBI::st. The MySubDBI root class itself isn't currently used for anything visible and so, apart from setting @ISA to include DBI, it can be left empty. (TBT)

So, having put your overriding methods into the right classes, and setup the inheritance hierarchy, how do you get the DBI to use them? You have two choices, either a static method call using the name of your subclass:

So, having put your overriding methods into the right classes, and setup the inheritance hierarchy, how do you get the DBI to use them? You have two choices, either a static method call using the name of your subclass: (TBT)

  $dbh = MySubDBI->connect(...);

or specifying a RootClass attribute:

または RootClass 属性を指定して:

  $dbh = DBI->connect(..., { RootClass => 'MySubDBI' });

If both forms are used then the attribute takes precedence.

両方の形式が使われると、属性が優先されます。

The only differences between the two are that using an explicit RootClass attribute will a) make the DBI automatically attempt to load a module by that name if the class doesn't exist, and b) won't call your MySubDBI::connect() method, if you have one.

The only differences between the two are that using an explicit RootClass attribute will a) make the DBI automatically attempt to load a module by that name if the class doesn't exist, and b) won't call your MySubDBI::connect() method, if you have one. (TBT)

When subclassing is being used then, after a successful new connect, the DBI->connect method automatically calls:

When subclassing is being used then, after a successful new connect, the DBI->connect method automatically calls: (TBT)

  $dbh->connected($dsn, $user, $pass, \%attr);

The default method does nothing. The call is made just to simplify any post-connection setup that your subclass may want to perform. The parameters are the same as passed to DBI->connect. If your subclass supplies a connected method, it should be part of the MySubDBI::db package.

The default method does nothing. The call is made just to simplify any post-connection setup that your subclass may want to perform. The parameters are the same as passed to DBI->connect. If your subclass supplies a connected method, it should be part of the MySubDBI::db package. (TBT)

One more thing to note: you must let the DBI do the handle creation. If you want to override the connect() method in your *::dr class then it must still call SUPER::connect to get a $dbh to work with. Similarly, an overridden prepare() method in *::db must still call SUPER::prepare to get a $sth. If you try to create your own handles using bless() then you'll find the DBI will reject them with an "is not a DBI handle (has no magic)" error.

One more thing to note: you must let the DBI do the handle creation. If you want to override the connect() method in your *::dr class then it must still call SUPER::connect to get a $dbh to work with. Similarly, an overridden prepare() method in *::db must still call SUPER::prepare to get a $sth. If you try to create your own handles using bless() then you'll find the DBI will reject them with an "is not a DBI handle (has no magic)" error. (TBT)

Here's a brief example of a DBI subclass. A more thorough example can be found in t/subclass.t in the DBI distribution.

Here's a brief example of a DBI subclass. A more thorough example can be found in t/subclass.t in the DBI distribution. (TBT)

  package MySubDBI;

  use strict;

  use DBI;
  use vars qw(@ISA);
  @ISA = qw(DBI);

  package MySubDBI::db;
  use vars qw(@ISA);
  @ISA = qw(DBI::db);

  sub prepare {
    my ($dbh, @args) = @_;
    my $sth = $dbh->SUPER::prepare(@args)
        or return;
    $sth->{private_mysubdbi_info} = { foo => 'bar' };
    return $sth;
  }

  package MySubDBI::st;
  use vars qw(@ISA);
  @ISA = qw(DBI::st);

  sub fetch {
    my ($sth, @args) = @_;
    my $row = $sth->SUPER::fetch(@args)
        or return;
    do_something_magical_with_row_data($row)
        or return $sth->set_err(1234, "The magic failed", undef, "fetch");
    return $row;
  }

When calling a SUPER::method that returns a handle, be careful to check the return value before trying to do other things with it in your overridden method. This is especially important if you want to set a hash attribute on the handle, as Perl's autovivification will bite you by (in)conveniently creating an unblessed hashref, which your method will then return with usually baffling results later on like the error "dbih_getcom handle HASH(0xa4451a8) is not a DBI handle (has no magic". It's best to check right after the call and return undef immediately on error, just like DBI would and just like the example above.

When calling a SUPER::method that returns a handle, be careful to check the return value before trying to do other things with it in your overridden method. This is especially important if you want to set a hash attribute on the handle, as Perl's autovivification will bite you by (in)conveniently creating an unblessed hashref, which your method will then return with usually baffling results later on like the error "dbih_getcom handle HASH(0xa4451a8) is not a DBI handle (has no magic". It's best to check right after the call and return undef immediately on error, just like DBI would and just like the example above. (TBT)

If your method needs to record an error it should call the set_err() method with the error code and error string, as shown in the example above. The error code and error string will be recorded in the handle and available via $h->err and $DBI::errstr etc. The set_err() method always returns an undef or empty list as appropriate. Since your method should nearly always return an undef or empty list as soon as an error is detected it's handy to simply return what set_err() returns, as shown in the example above.

If your method needs to record an error it should call the set_err() method with the error code and error string, as shown in the example above. The error code and error string will be recorded in the handle and available via $h->err and $DBI::errstr etc. The set_err() method always returns an undef or empty list as appropriate. Since your method should nearly always return an undef or empty list as soon as an error is detected it's handy to simply return what set_err() returns, as shown in the example above. (TBT)

If the handle has RaiseError, PrintError, or HandleError etc. set then the set_err() method will honour them. This means that if RaiseError is set then set_err() won't return in the normal way but will 'throw an exception' that can be caught with an eval block.

If the handle has RaiseError, PrintError, or HandleError etc. set then the set_err() method will honour them. This means that if RaiseError is set then set_err() won't return in the normal way but will 'throw an exception' that can be caught with an eval block. (TBT)

You can stash private data into DBI handles via $h->{private_..._*}. See the entry under "ATTRIBUTES COMMON TO ALL HANDLES" for info and important caveats.

You can stash private data into DBI handles via $h->{private_..._*}. See the entry under "ATTRIBUTES COMMON TO ALL HANDLES" for info and important caveats. (TBT)

トレース

The DBI has a powerful tracing mechanism built in. It enables you to see what's going on 'behind the scenes', both within the DBI and the drivers you're using.

The DBI has a powerful tracing mechanism built in. It enables you to see what's going on 'behind the scenes', both within the DBI and the drivers you're using. (TBT)

トレース設定

Which details are written to the trace output is controlled by a combination of a trace level, an integer from 0 to 15, and a set of trace flags that are either on or off. Together these are known as the trace settings and are stored together in a single integer. For normal use you only need to set the trace level, and generally only to a value between 1 and 4.

Which details are written to the trace output is controlled by a combination of a trace level, an integer from 0 to 15, and a set of trace flags that are either on or off. Together these are known as the trace settings and are stored together in a single integer. For normal use you only need to set the trace level, and generally only to a value between 1 and 4. (TBT)

Each handle has it's own trace settings, and so does the DBI. When you call a method the DBI merges the handles settings into its own for the duration of the call: the trace flags of the handle are OR'd into the trace flags of the DBI, and if the handle has a higher trace level then the DBI trace level is raised to match it. The previous DBI trace settings are restored when the called method returns.

Each handle has it's own trace settings, and so does the DBI. When you call a method the DBI merges the handles settings into its own for the duration of the call: the trace flags of the handle are OR'd into the trace flags of the DBI, and if the handle has a higher trace level then the DBI trace level is raised to match it. The previous DBI trace settings are restored when the called method returns. (TBT)

トレースレベル

Trace levels are as follows:

トレース レベル は以下のようになります:

  0 - Trace disabled.
  1 - Trace top-level DBI method calls returning with results or errors.
  2 - As above, adding tracing of top-level method entry with parameters.
  3 - As above, adding some high-level information from the driver
      and some internal information from the DBI.
  4 - As above, adding more detailed information from the driver.
      This is the first level to trace all the rows being fetched.
  5 to 15 - As above but with more and more internal information.
  0 - トレース無効
  1 - トップレベル DBI メソッド呼び出しの戻りを結果またはエラーと一緒にトレース
  2 - 加えてトップレベルメソッドのエントリをパラメータと一緒にトレース
  3 - 加えてドライバからのいくつかのハイレベルな情報と
      DBIからのいくつかの内部情報を追加。
  4 - 加えてドライバからのさらに詳細な情報を追加。
      これはフェッチされる全ての行をトレースする最初のレベルです。
  5 から 15 - 上記と同様。しかし大きくなるに従ってさらに内部の情報。

Trace level 1 is best for a simple overview of what's happening. Trace levels 2 thru 4 a good choice for general purpose tracing. Levels 5 and above are best reserved for investigating a specific problem, when you need to see "inside" the driver and DBI.

トレースレベル 1 が何が起こったのかの単純な概要のために最も向いています。 トレースレベル 2 から 4 はトレースの一般的な目的にはよい選択です。 レベル 5 以上は、DBIとドライバの「内部」を見る必要があるとき、 特定の問題を調べるために予約されています。

The trace output is detailed and typically very useful. Much of the trace output is formatted using the "neat" function, so strings in the trace output may be edited and truncated by that function.

トレース出力はとても詳細で、普通とても役に立ちます。 トレース出力の多くが "neat" 関数を使って形式を整えています。 このためトレース出力での文字列はこの関数によって編集され、 切り捨てられているかもしれません。。

トレースフラグ

Trace flags are used to enable tracing of specific activities within the DBI and drivers. The DBI defines some trace flags and drivers can define others. DBI trace flag names begin with a capital letter and driver specific names begin with a lowercase letter, as usual.

トレース フラグ は DBI とドライバの内部の特定の機能のトレースを 有効にするために使われます。 DBI がいくつかのトレースフラグを定義し、ドライバもいくつか定義します。 通常通り、DBI のトレースフラグ名は大文字で始まり、ドライバ固有の名前は 小文字で始まります。

Currently the DBI only defines two trace flags:

現在のところ DBI は二つのトレースフラグのみを定義しています:

  ALL - turn on all DBI and driver flags (not recommended)
  SQL - trace SQL statements executed
        (not yet implemented in DBI but implemented in some DBDs)
  ALL - 全ての DBI とドライバのフラグを有効にする (勧めません)
  SQL - 実行された SQL 文をトレースする
        (まだ DBI には実装されていませんが一部の DBD で実装されています)

The "parse_trace_flags" and "parse_trace_flag" methods are used to convert trace flag names into the corresponding integer bit flags.

"parse_trace_flags" メソッドと "parse_trace_flag" メソッドは トレースフラグ名を対応する整数ビットフラグに変換するために使われます。

トレースを有効にする

The $h->trace method sets the trace settings for a handle and DBI->trace does the same for the DBI.

$h->trace メソッドはハンドルのためのトレース設定を設定し、 DBI->trace は DBI のためのものです。

In addition to the "trace" method, you can enable the same trace information, and direct the output to a file, by setting the DBI_TRACE environment variable before starting Perl. See "DBI_TRACE" for more information.

"trace" メソッドに加えて、Perl を実行する前に環境変数 DBI_TRACE を 設定すれば、同じトレース情報を有効にし、ファイルに出力することができます。 さらなる情報については "DBI_TRACE" を参照してください。

Finally, you can set, or get, the trace settings for a handle using the TraceLevel attribute.

最後に、ハンドルのトレース設定は TraceLevel 属性を使って 設定・取得できます。

All of those methods use parse_trace_flags() and so allow you set both the trace level and multiple trace flags by using a string containing the trace level and/or flag names separated by vertical bar ("|") or comma (",") characters. For example:

これら全てのメソッドは parse_trace_flags() を使っているので、 トレースレベルとフラグ名を縦棒 ("|") またはカンマ (",") 文字で 区切った文字列を使うことでトレースレベルと複数のトレースフラグの同時に 設定できます。 例えば:

  local $h->{TraceLevel} = "3|SQL|foo";

トレース出力

Initially trace output is written to STDERR. Both the $h->trace and DBI->trace methods take an optional $trace_file parameter, which may be either the name of a file to be opened by DBI in append mode, or a reference to an existing writable (possibly layered) filehandle. If $trace_file is a filename, and can be opened in append mode, or $trace_file is a writable filehandle, then all trace output (currently including that from other handles) is redirected to that file. A warning is generated if $trace_file can't be opened or is not writable.

Initially trace output is written to STDERR. Both the $h->trace and DBI->trace methods take an optional $trace_file parameter, which may be either the name of a file to be opened by DBI in append mode, or a reference to an existing writable (possibly layered) filehandle. If $trace_file is a filename, and can be opened in append mode, or $trace_file is a writable filehandle, then all trace output (currently including that from other handles) is redirected to that file. A warning is generated if $trace_file can't be opened or is not writable. (TBT)

Further calls to trace() without $trace_file do not alter where the trace output is sent. If $trace_file is undefined, then trace output is sent to STDERR and, if the prior trace was opened with $trace_file as a filename, the previous trace file is closed; if $trace_file was a filehandle, the filehandle is not closed.

Further calls to trace() without $trace_file do not alter where the trace output is sent. If $trace_file is undefined, then trace output is sent to STDERR and, if the prior trace was opened with $trace_file as a filename, the previous trace file is closed; if $trace_file was a filehandle, the filehandle is not closed. (TBT)

NOTE: If $trace_file is specified as a filehandle, the filehandle should not be closed until all DBI operations are completed, or the application has reset the trace file via another call to trace() that changes the trace file.

NOTE: If $trace_file is specified as a filehandle, the filehandle should not be closed until all DBI operations are completed, or the application has reset the trace file via another call to trace() that changes the trace file. (TBT)

層のあるファイルハンドルへのトレース

NOTE:

注意:

  • Tied filehandles are not currently supported, as tie operations are not available to the PerlIO methods used by the DBI.

    tie されたファイルハンドルは現在のところ対応していません; tie 操作は DBI で使っている PerlIO で利用できないからです。

  • PerlIO layer support requires Perl version 5.8 or higher.

    PerlIO 層対応は Perl バージョン 5.8 以降が必要です。

As of version 5.8, Perl provides the ability to layer various "disciplines" on an open filehandle via the PerlIO module.

バージョン 5.8 から、Perl は開いたファイルハンドルに対して PerlIO モジュールを通して様々な「ディシプリン」を積み重ねる機能を 提供しています。

A simple example of using PerlIO layers is to use a scalar as the output:

PerlIO 層を使った簡単な例はスカラを出力として使います:

    my $scalar = '';
    open( my $fh, "+>:scalar", \$scalar );
    $dbh->trace( 2, $fh );

Now all trace output is simply appended to $scalar.

ここで全てのトレース出力は単純に $scalar に追加されます。

A more complex application of tracing to a layered filehandle is the use of a custom layer (Refer to Perlio::via for details on creating custom PerlIO layers.). Consider an application with the following logger module:

A more complex application of tracing to a layered filehandle is the use of a custom layer (Refer to Perlio::via for details on creating custom PerlIO layers.). Consider an application with the following logger module: (TBT)

    package MyFancyLogger;

    sub new
    {
        my $self = {};
        my $fh;
        open $fh, '>', 'fancylog.log';
        $self->{_fh} = $fh;
        $self->{_buf} = '';
        return bless $self, shift;
    }

    sub log
    {
        my $self = shift;
        return unless exists $self->{_fh};
        my $fh = $self->{_fh};
        $self->{_buf} .= shift;
    #
    # DBI feeds us pieces at a time, so accumulate a complete line
    # before outputing
    #
        print $fh "At ", scalar localtime(), ':', $self->{_buf}, "\n" and
        $self->{_buf} = ''
            if $self->{_buf}=~tr/\n//;
    }

    sub close {
        my $self = shift;
        return unless exists $self->{_fh};
        my $fh = $self->{_fh};
        print $fh "At ", scalar localtime(), ':', $self->{_buf}, "\n" and
        $self->{_buf} = ''
            if $self->{_buf};
        close $fh;
        delete $self->{_fh};
    }

    1;

To redirect DBI traces to this logger requires creating a package for the layer:

DBI トレースをこのロガーにリダイレクトするには、層のためのパッケージを作る 必要があります:

    package PerlIO::via::MyFancyLogLayer;

    sub PUSHED
    {
        my ($class,$mode,$fh) = @_;
        my $logger;
        return bless \$logger,$class;
    }

    sub OPEN {
        my ($self, $path, $mode, $fh) = @_;
        #
        # $path is actually our logger object
        #
        $$self = $path;
        return 1;
    }

    sub WRITE
    {
        my ($self, $buf, $fh) = @_;
        $$self->log($buf);
        return length($buf);
    }

    sub CLOSE {
        my $self = shift;
        $$self->close();
        return 0;
    }

    1;

The application can then cause DBI traces to be routed to the logger using

The application can then cause DBI traces to be routed to the logger using (TBT)

    use PerlIO::via::MyFancyLogLayer;

    open my $fh, '>:via(MyFancyLogLayer)', MyFancyLogger->new();

    $dbh->trace('SQL', $fh);

Now all trace output will be processed by MyFancyLogger's log() method.

ここで全てのトレース出力は MyFancyLogger の log() メソッドによって 処理されます。

トレースの内容

Many of the values embedded in trace output are formatted using the neat() utility function. This means they may be quoted, sanitized, and possibly truncated if longer than $DBI::neat_maxlen. See "neat" for more details.

トレース出力に含まれている値の多くは neat() ユーティリティ関数を使って フォーマットされます。 つまり、クォートされ、サニタイズされ、$DBI::neat_maxlen より長い場合は 切り詰められるかもしれないことを意味します。 さらなる詳細については "neat" を参照してください。

トレースの小技

You can add tracing to your own application code using the "trace_msg" method.

"trace_msg" メソッドを使って自身のアプリケーションにトレースを 追加できます。

It can sometimes be handy to compare trace files from two different runs of the same script. However using a tool like diff on the original log output doesn't work well because the trace file is full of object addresses that may differ on each run.

It can sometimes be handy to compare trace files from two different runs of the same script. However using a tool like diff on the original log output doesn't work well because the trace file is full of object addresses that may differ on each run. (TBT)

The DBI includes a handy utility called dbilogstrip that can be used to 'normalize' the log content. It can be used as a filter like this:

The DBI includes a handy utility called dbilogstrip that can be used to 'normalize' the log content. It can be used as a filter like this: (TBT)

    DBI_TRACE=2 perl yourscript.pl ...args1... 2>&1 | dbilogstrip > dbitrace1.log
    DBI_TRACE=2 perl yourscript.pl ...args2... 2>&1 | dbilogstrip > dbitrace2.log
    diff -u dbitrace1.log dbitrace2.log

See dbilogstrip for more information.

さらなる情報については dbilogstrip を参照してください。

DBI 環境変数

The DBI module recognizes a number of environment variables, but most of them should not be used most of the time. It is better to be explicit about what you are doing to avoid the need for environment variables, especially in a web serving system where web servers are stingy about which environment variables are available.

The DBI module recognizes a number of environment variables, but most of them should not be used most of the time. It is better to be explicit about what you are doing to avoid the need for environment variables, especially in a web serving system where web servers are stingy about which environment variables are available. (TBT)

DBI_DSN

The DBI_DSN environment variable is used by DBI->connect if you do not specify a data source when you issue the connect. It should have a format such as "dbi:Driver:databasename".

The DBI_DSN environment variable is used by DBI->connect if you do not specify a data source when you issue the connect. It should have a format such as "dbi:Driver:databasename". (TBT)

DBI_DRIVER

The DBI_DRIVER environment variable is used to fill in the database driver name in DBI->connect if the data source string starts "dbi::" (thereby omitting the driver). If DBI_DSN omits the driver name, DBI_DRIVER can fill the gap.

The DBI_DRIVER environment variable is used to fill in the database driver name in DBI->connect if the data source string starts "dbi::" (thereby omitting the driver). If DBI_DSN omits the driver name, DBI_DRIVER can fill the gap. (TBT)

DBI_AUTOPROXY

The DBI_AUTOPROXY environment variable takes a string value that starts "dbi:Proxy:" and is typically followed by "hostname=...;port=...". It is used to alter the behaviour of DBI->connect. For full details, see DBI::Proxy documentation.

The DBI_AUTOPROXY environment variable takes a string value that starts "dbi:Proxy:" and is typically followed by "hostname=...;port=...". It is used to alter the behaviour of DBI->connect. For full details, see DBI::Proxy documentation. (TBT)

DBI_USER

The DBI_USER environment variable takes a string value that is used as the user name if the DBI->connect call is given undef (as distinct from an empty string) as the username argument. Be wary of the security implications of using this.

The DBI_USER environment variable takes a string value that is used as the user name if the DBI->connect call is given undef (as distinct from an empty string) as the username argument. Be wary of the security implications of using this. (TBT)

DBI_PASS

The DBI_PASS environment variable takes a string value that is used as the password if the DBI->connect call is given undef (as distinct from an empty string) as the password argument. Be extra wary of the security implications of using this.

The DBI_PASS environment variable takes a string value that is used as the password if the DBI->connect call is given undef (as distinct from an empty string) as the password argument. Be extra wary of the security implications of using this. (TBT)

DBI_DBNAME (obsolete)

The DBI_DBNAME environment variable takes a string value that is used only when the obsolescent style of DBI->connect (with driver name as fourth parameter) is used, and when no value is provided for the first (database name) argument.

The DBI_DBNAME environment variable takes a string value that is used only when the obsolescent style of DBI->connect (with driver name as fourth parameter) is used, and when no value is provided for the first (database name) argument. (TBT)

DBI_TRACE

The DBI_TRACE environment variable specifies the global default trace settings for the DBI at startup. Can also be used to direct trace output to a file. When the DBI is loaded it does:

The DBI_TRACE environment variable specifies the global default trace settings for the DBI at startup. Can also be used to direct trace output to a file. When the DBI is loaded it does: (TBT)

  DBI->trace(split /=/, $ENV{DBI_TRACE}, 2) if $ENV{DBI_TRACE};

So if DBI_TRACE contains an "=" character then what follows it is used as the name of the file to append the trace to.

So if DBI_TRACE contains an "=" character then what follows it is used as the name of the file to append the trace to. (TBT)

output appended to that file. If the name begins with a number followed by an equal sign (=), then the number and the equal sign are stripped off from the name, and the number is used to set the trace level. For example:

出力はこのファイルに追加されます。 もしファイル名が数字で始まり、後ろに等号(=)がついているのであれば、 数字と等号は名前から切り離され、数字はトレースレベルを設定するのに 使われます。 例えば:

  DBI_TRACE=1=dbitrace.log perl your_test_script.pl

On Unix-like systems using a Bourne-like shell, you can do this easily on the command line:

unix のようなシステムで Bourne のようなシェルを使っていれば、これを コマンドラインで簡単に行うことができます:

  DBI_TRACE=2 perl your_test_script.pl

See "TRACING" for more information.

さらなる情報については "TRACING" を参照してください。

PERL_DBI_DEBUG (obsolete)

An old variable that should no longer be used; equivalent to DBI_TRACE.

もはや使うべきではない古い変数です; DBI_TRACE と等価です。

DBI_PROFILE

The DBI_PROFILE environment variable can be used to enable profiling of DBI method calls. See DBI::Profile for more information.

DBI_PROFILE 環境変数は DBI メソッド呼び出しのプロファイリングを 有効にするために使われます。 さらなる情報については DBI::Profile を参照してください。

DBI_PUREPERL

The DBI_PUREPERL environment variable can be used to enable the use of DBI::PurePerl. See DBI::PurePerl for more information.

DBI_PUREPERL 環境変数は DBI::PurePerl の使用を有効にするために 使われます。 さらなる情報については DBI::PurePerl を参照してください。

警告とエラーメッセージ

致命的エラー

Can't call method "prepare" without a package or object reference

The $dbh handle you're using to call prepare is probably undefined because the preceding connect failed. You should always check the return status of DBI methods, or use the "RaiseError" attribute.

おそらく以前の connect が失敗したために、prepare 呼び出しに使った $dbh ハンドルが未定義です。 DBI メソッドの戻りステータスを常にチェックするか、"RaiseError" 属性を 使わなければりません。

Can't call method "execute" without a package or object reference

The $sth handle you're using to call execute is probably undefined because the preceding prepare failed. You should always check the return status of DBI methods, or use the "RaiseError" attribute.

おそらく以前の prepare メソッドが失敗したために、execute 呼び出しに 使った $sth ハンドルが未定義です。 DBI メソッドの戻りステータスを常にチェックするか、"RaiseError" 属性を 使わなければりません。

DBI/DBD internal version mismatch

The DBD driver module was built with a different version of DBI than the one currently being used. You should rebuild the DBD module under the current version of DBI.

DBD ドライバモジュールが、現在使っている DBI とは異なるバージョンで ビルドされています。 現在のバージョンの DBI のもとで DBD モジュールを リビルドしなければなりません。

(Some rare platforms require "static linking". On those platforms, there may be an old DBI or DBD driver version actually embedded in the Perl executable being used.)

(まれにですが、いくつかプラットホームは「静的リンク」(static linking) を 要求します。 古い DBI もしくは DBD ドライバが、使われている Perl の実行可能ファイルに 実際に埋め込まれているのかもしれません。)

DBD driver has not implemented the AutoCommit attribute

The DBD driver implementation is incomplete. Consult the author.

DBD ドライバの実装が完全ではありません。 作者に聞いてみてください。

Can't [sg]et %s->{%s}: unrecognised attribute

You attempted to set or get an unknown attribute of a handle. Make sure you have spelled the attribute name correctly; case is significant (e.g., "Autocommit" is not the same as "AutoCommit").

ハンドルの不明な属性を設定または取得しようとしました。 属性の名前が正しいかを確認してください; 大文字/小文字は意味があります (例えば "Autocommit" は "AutoCommit" と同じではありません)。

ピュア Perl の DBI

A pure-perl emulation of the DBI is included in the distribution for people using pure-perl drivers who, for whatever reason, can't install the compiled DBI. See DBI::PurePerl.

なんらかの理由によってコンパイルされた DBI をインストールできないために ピュア Perl ドライバを使う人々のために、DBI の ピュア Perl エミュレーションがこの配布に含まれています。 DBI::PurePerl を参照してください。

SEE ALSO

ドライバとデータベースのドキュメント

Refer to the documentation for the DBD driver that you are using.

使っている DBD ドライバのドキュメントをご覧下さい。

Refer to the SQL Language Reference Manual for the database engine that you are using.

使っているデータベース・エンジンのための SQL 言語 リファレンスマニュアルをご覧下さい。

ODBC と SQL/CLI 標準の参照情報

More detailed information about the semantics of certain DBI methods that are based on ODBC and SQL/CLI standards is available on-line via microsoft.com, for ODBC, and www.jtc1sc32.org for the SQL/CLI standard:

More detailed information about the semantics of certain DBI methods that are based on ODBC and SQL/CLI standards is available on-line via microsoft.com, for ODBC, and www.jtc1sc32.org for the SQL/CLI standard: (TBT)

 DBI method        ODBC function     SQL/CLI Working Draft
 ----------        -------------     ---------------------
 column_info       SQLColumns        Page 124
 foreign_key_info  SQLForeignKeys    Page 163
 get_info          SQLGetInfo        Page 214
 primary_key_info  SQLPrimaryKeys    Page 254
 table_info        SQLTables         Page 294
 type_info         SQLGetTypeInfo    Page 239
 statistics_info   SQLStatistics

To find documentation on the ODBC function you can use the MSDN search facility at:

To find documentation on the ODBC function you can use the MSDN search facility at: (TBT)

    http://msdn.microsoft.com/Search

and search for something like "SQLColumns returns".

そして "SQLColumns returns" のような形で検索してください。

And for SQL/CLI standard information on SQLColumns you'd read page 124 of the (very large) SQL/CLI Working Draft available from:

And for SQL/CLI standard information on SQLColumns you'd read page 124 of the (very large) SQL/CLI Working Draft available from: (TBT)

  http://jtc1sc32.org/doc/N0701-0750/32N0744T.pdf

標準の参照情報

A hyperlinked, browsable version of the BNF syntax for SQL92 (plus Oracle 7 SQL and PL/SQL) is available here:

A hyperlinked, browsable version of the BNF syntax for SQL92 (plus Oracle 7 SQL and PL/SQL) is available here: (TBT)

  http://cui.unige.ch/db-research/Enseignement/analyseinfo/SQL92/BNFindex.html

A BNF syntax for SQL3 is available here:

SQL3 の BNF 文法は以下で利用可能です:

  http://www.sqlstandards.org/SC32/WG3/Progression_Documents/Informal_working_drafts/iso-9075-2-1999.bnf

The following links provide further useful information about SQL. Some of these are rather dated now but may still be useful.

The following links provide further useful information about SQL. Some of these are rather dated now but may still be useful. (TBT)

  http://www.jcc.com/SQLPages/jccs_sql.htm
  http://www.contrib.andrew.cmu.edu/~shadow/sql.html
  http://www.altavista.com/query?q=sql+tutorial

書籍と記事

Programming the Perl DBI, by Alligator Descartes and Tim Bunce. http://books.perl.org/book/154

Programming the Perl DBI, by Alligator Descartes and Tim Bunce. http://books.perl.org/book/154 (訳注: 入門Perl DBI)

Programming Perl 3rd Ed. by Larry Wall, Tom Christiansen & Jon Orwant. http://books.perl.org/book/134

Programming Perl 3rd Ed. by Larry Wall, Tom Christiansen & Jon Orwant. http://books.perl.org/book/134 (訳注: プログラミング Perl)

Learning Perl by Randal Schwartz. http://books.perl.org/book/101

Learning Perl by Randal Schwartz. http://books.perl.org/book/101 (訳注: 初めてのPerl)

Details of many other books related to perl can be found at http://books.perl.org

その他の perl に関する多くの本の詳細は http://books.perl.org にあります。

Perl モジュール

Index of DBI related modules available from CPAN:

CPAN から利用可能な DBI 関連モジュールのインデックス:

 http://search.cpan.org/search?mode=module&query=DBIx%3A%3A
 http://search.cpan.org/search?mode=doc&query=DBI

For a good comparison of RDBMS-OO mappers and some OO-RDBMS mappers (including Class::DBI, Alzabo, and DBIx::RecordSet in the former category and Tangram and SPOPS in the latter) see the Perl Object-Oriented Persistence project pages at:

RDBMS-OO マッパーと OO-RDBMS マッパー(前者は Class::DBI, Alzabo, DBIx::RecordSet、後者は Tangram と SPOPS)の良い比較については 以下の Perl Object-Oriented Persistence プロジェクトを参照してください:

 http://poop.sourceforge.net

A similar page for Java toolkits can be found at:

Java ツールキットのための似たようなページは以下にあります:

 http://c2.com/cgi-bin/wiki?ObjectRelationalToolComparison

メーリングリスト

The dbi-users mailing list is the primary means of communication among users of the DBI and its related modules. For details send email to:

dbi-users メーリングリストは DBI とその関連するモジュールの利用者の コミュニケーションを第一の目的としています。 詳細については下記のアドレスにメールを送ってください:

 dbi-users-help@perl.org

There are typically between 700 and 900 messages per month. You have to subscribe in order to be able to post. However you can opt for a 'post-only' subscription.

通常 1 ヶ月に 700 から 900 のメッセージがあります。 投稿できるようになるためには加入しなければなりません。 しかしオプションで「投稿のみ」(post-only)の参加を選択することができます。

Mailing list archives (of variable quality) are held at:

(様々な品質の) メーリングリストのアーカイブは以下のサイトにあります:

 http://groups.google.com/groups?group=perl.dbi.users
 http://www.xray.mpe.mpg.de/mailing-lists/dbi/
 http://www.mail-archive.com/dbi-users%40perl.org/

The DBI "Home Page":

DBI "ホームページ":

 http://dbi.perl.org/

Other DBI related links:

その他のDBI関連のリンク:

 http://tegan.deltanet.com/~phlip/DBUIdoc.html
 http://dc.pm.org/perl_db.html
 http://wdvl.com/Authoring/DB/Intro/toc.html
 http://www.hotwired.com/webmonkey/backend/tutorials/tutorial1.html
 http://bumppo.net/lists/macperl/1999/06/msg00197.html
 http://gmax.oltrelinux.com/dbirecipes.html

Other database related links:

その他のデータベース関連のリンク:

 http://www.jcc.com/sql_stnd.html
 http://cuiwww.unige.ch/OSG/info/FreeDB/FreeDB.home.html
 http://www.connectionstrings.com/

Security, especially the "SQL Injection" attack:

セキュリティ、特に「SQL インジェクション」攻撃:

 http://www.ngssoftware.com/research/papers.html
 http://www.ngssoftware.com/papers/advanced_sql_injection.pdf
 http://www.ngssoftware.com/papers/more_advanced_sql_injection.pdf
 http://www.esecurityplanet.com/trends/article.php/2243461
 http://www.spidynamics.com/papers/SQLInjectionWhitePaper.pdf
 http://www.imperva.com/application_defense_center/white_papers/blind_sql_server_injection.html
 http://online.securityfocus.com/infocus/1644

Commercial and Data Warehouse Links

商用およびデータウェアハウスのリンク:

 http://www.dwinfocenter.org
 http://www.datawarehouse.com
 http://www.datamining.org
 http://www.olapcouncil.org
 http://www.idwa.org
 http://www.knowledgecenters.org/dwcenter.asp

Recommended Perl Programming Links

推奨される Perl プログラミングのリンク

 http://language.perl.com/style/

FAQ

http://faq.dbi-support.com/ を参照してください。

作者

DBI by Tim Bunce, http://www.tim.bunce.name

DBI は Tim Bunce, http://www.tim.bunce.name

This pod text by Tim Bunce, J. Douglas Dunlop, Jonathan Leffler and others. Perl by Larry Wall and the perl5-porters.

この pod 文書は Tim Bunce, J. Douglas Dunlop, Jonathan Leffler および その他の人たち。 Perl は Larry Wall および the perl5-porters

コピーライト

The DBI module is Copyright (c) 1994-2009 Tim Bunce. Ireland. All rights reserved.

You may distribute under the terms of either the GNU General Public License or the Artistic License, as specified in the Perl 5.10.0 README file.

サポート / 保証

The DBI is free Open Source software. IT COMES WITHOUT WARRANTY OF ANY KIND.

DBI はオープンソースソフトウェアです。 いかなる保証もおこないません。

サポート

My consulting company, Data Plan Services, offers annual and multi-annual support contracts for the DBI. These provide sustained support for DBI development, and sustained value for you in return. Contact me for details.

私のコンサルタント会社である Data Plan Services は DBI に対する一年および 複数年のサポート契約を提供しています。 これらは DBI 開発に対する持続的なサポートを提供し、あなたに持続的な 価値を提供します。 詳しくは私に連絡を取ってください。

スポンサー拡張

The DBI Roadmap is available at http://search.cpan.org/~timb/DBI/Roadmap.pod

DBI ロードマップは http://search.cpan.org/~timb/DBI/Roadmap.pod に あります。

If your company would benefit from a specific new DBI feature, please consider sponsoring its development. Work is performed rapidly, and usually on a fixed-price payment-on-delivery basis. Contact me for details.

If your company would benefit from a specific new DBI feature, please consider sponsoring its development. Work is performed rapidly, and usually on a fixed-price payment-on-delivery basis. Contact me for details. (TBT)

Using such targeted financing allows you to contribute to DBI development, and rapidly get something specific and valuable in return.

Using such targeted financing allows you to contribute to DBI development, and rapidly get something specific and valuable in return. (TBT)

謝辞

I would like to acknowledge the valuable contributions of the many people I have worked with on the DBI project, especially in the early years (1992-1994). In no particular order: Kevin Stock, Buzz Moschetti, Kurt Andersen, Ted Lemon, William Hails, Garth Kennedy, Michael Peppler, Neil S. Briscoe, Jeff Urlwin, David J. Hughes, Jeff Stander, Forrest D Whitcher, Larry Wall, Jeff Fried, Roy Johnson, Paul Hudson, Georg Rehfeld, Steve Sizemore, Ron Pool, Jon Meek, Tom Christiansen, Steve Baumgarten, Randal Schwartz, and a whole lot more.

DBIプロジェクトで、とりわけ最初のころ(1992-1994)に、多大な貢献してくれた 多くの人に感謝します。 順不同で、Kevin Stock, Buzz Moschetti, Kurt Andersen, Ted Lemon, William Hails, Garth Kennedy, Michael Peppler, Neil S. Briscoe, Jeff Urlwin, David J. Hughes, Jeff Stander, Forrest D Whitcher, Larry Wall, Jeff Fried, Roy Johnson, Paul Hudson, Georg Rehfeld, Steve Sizemore, Ron Pool, Jon Meek, Tom Christiansen, Steve Baumgarten, Randal Schwartz 他の多くのみなさん。

Then, of course, there are the poor souls who have struggled through untold and undocumented obstacles to actually implement DBI drivers. Among their ranks are Jochen Wiedmann, Alligator Descartes, Jonathan Leffler, Jeff Urlwin, Michael Peppler, Henrik Tougaard, Edwin Pratomo, Davide Migliavacca, Jan Pazdziora, Peter Haworth, Edmund Mergl, Steve Williams, Thomas Lowery, and Phlip Plumlee. Without them, the DBI would not be the practical reality it is today. I'm also especially grateful to Alligator Descartes for starting work on the first edition of the "Programming the Perl DBI" book and letting me jump on board.

そしてもちろん、DBI ドライバ実装への語られないそして文書化されていない 障害と葛藤し、やりとげた哀れな人々にも。 順番をつけると、Jochen Wiedmann, Alligator Descartes, Jonathan Leffler, Jeff Urlwin, Michael Peppler, Henrik Tougaard, Edwin Pratomo, Davide Migliavacca, Jan Pazdziora, Peter Haworth, Edmund Mergl, Steve Williams, Thomas Lowery, Phlip Plumlee。 彼ら無しには DBI は今日のような実際のリアリテイをもたなかったでしょう。 また本 "Programming the Perl DBI" 第一版を始め、参加させてくれた Alligator Descartes にも特に感謝します。

The DBI and DBD::Oracle were originally developed while I was Technical Director (CTO) of Ingeneering in the UK (http://www.ig.co.uk) (formerly known as the Paul Ingram Group). So I'd especially like to thank Paul for his generosity and vision in supporting this work for many years.

DBI と DBD::Oracle はもともと私がイギリスの (以前は Paul Ingram Group として 知られていた) Ingeneering の CTO であった間に開発されました。 それで、長年にわたってこの作業を支えてくれた寛大さと先見性に対して、 特に Paul に感謝したいと思います。

A couple of specific DBI features have been sponsored by enlightened companies:

二つの DBI 機能は啓発的な企業によりスポンサーされました:

The development of the swap_inner_handle() method was sponsored by BizRate.com (http://BizRate.com)

swap_inner_handle() メソッドの開発は BizRate.com (http://BizRate.com) のスポンサーによるものです。

The development of DBD::Gofer and related modules was sponsored by Shopzilla.com (http://Shopzilla.com), where I currently work.

DBD::Gofer および関連するモジュールの開発は私が現在働いている Shopzilla.com (http://Shopzilla.com) のスポンサーによるものです。

寄与する

As you can see above, many people have contributed to the DBI and drivers in many ways over many years.

上述したように、多くの人々が長年にわたって様々な方法で DBI と ドライバに寄与してきました。

もし助けようと思ったなら、http://dbi.perl.org/contributinghttp://search.cpan.org/~timb/DBI/Roadmap.pod を参照してください。

If you'd like the DBI to do something new or different then a good way to make that happen is to do it yourself and send me a patch to the source code that shows the changes. (But read "Speak before you patch" below.)

DBI に対して何か新しいか異なったことをしようと思ったら、自分でそれを 行って、変更点が分かるソースコードのパッチを送ってください。 (しかし後述する "Speak before you patch" を読んでください。)

ソースコードレポジトリを見る

Use http://svn.perl.org/modules/dbi/trunk (basic) or http://svn.perl.org/viewcvs/modules/ (more useful)

http://svn.perl.org/modules/dbi/trunk (基本) か http://svn.perl.org/viewcvs/modules/ (より有用) を使ってください。

Subversion を使ってパッチを作る方法

The DBI source code is maintained using Subversion (a replacement for CVS, see http://subversion.tigris.org/). To access the source you'll need to install a Subversion client. Then, to get the source code, do:

DBI のソースコードは Subversion (CVS の代替物です; http://subversion.tigris.org/ を参照してください) を使って 保守されています。 ソースにアクセスするためには、Subversion クライアントを インストールする必要があります。 それから、ソースコードを取得するには、以下のようにします:

  svn checkout http://svn.perl.org/modules/dbi/trunk

If it prompts for a username and password use your perl.org account if you have one, else just 'guest' and 'guest'. The source code will be in a new subdirectory called trunk.

ユーザー名とパスワードを聞かれたら、もし perl.org のアカウントがあれば それを、さもなければ単に 'guest' と 'guest' を使ってください。 ソースコードは trunk と呼ばれる新しいディレクトリの下にあります。

To keep informed about changes to the source you can send an empty email to svn-commit-modules-dbi-subscribe@perl.org after which you'll get an email with the change log message and diff of each change checked-in to the source.

To keep informed about changes to the source you can send an empty email to svn-commit-modules-dbi-subscribe@perl.org after which you'll get an email with the change log message and diff of each change checked-in to the source. (TBT)

After making your changes you can generate a patch file, but before you do, make sure your source is still up to date using:

After making your changes you can generate a patch file, but before you do, make sure your source is still up to date using: (TBT)

  svn update

If you get any conflicts reported you'll need to fix them first. Then generate the patch file from within the trunk directory using:

If you get any conflicts reported you'll need to fix them first. Then generate the patch file from within the trunk directory using: (TBT)

  svn diff > foo.patch

Read the patch file, as a sanity check, and then email it to dbi-dev@perl.org.

サニティチェックとしてパッチファイルを読んでから、 dbi-dev@perl.org に メールを送ってください。

Subversion なしでパッチを作る方法

Unpack a fresh copy of the distribution:

最新版のディストリビューションを展開します:

  tar xfz DBI-1.40.tar.gz

Rename the newly created top level directory:

新しく作ったトップレベルディレクトリに名前を変えます:

  mv DBI-1.40 DBI-1.40.your_foo

Edit the contents of DBI-1.40.your_foo/* till it does what you want.

必要なだけ DBI-1.40.your_foo/* の内容を変更します。

Test your changes and then remove all temporary files:

変更をテストして、全ての一時ファイルを削除します:

  make test && make distclean

Go back to the directory you originally unpacked the distribution:

最初にディストリビューションを展開したディレクトリに戻ります:

  cd ..

Unpack another copy of the original distribution you started with:

元のディストリビューションを もう一度 展開します:

  tar xfz DBI-1.40.tar.gz

Then create a patch file by performing a recursive diff on the two top level directories:

二つのトップレベルディレクトリに対して再帰的に diff を実行することで パッチファイルを作成します:

  diff -r -u DBI-1.40 DBI-1.40.your_foo > DBI-1.40.your_foo.patch

パッチする前に話してみる

For anything non-trivial or possibly controversial it's a good idea to discuss (on dbi-dev@perl.org) the changes you propose before actually spending time working on them. Otherwise you run the risk of them being rejected because they don't fit into some larger plans you may not be aware of.

普通でない、あるいは議論の余地があるかもしれないものついては、 実際に作業に時間を費やす前に考えている変更について (dbi-dev@perl.org で)議論するのはよい考えです。 さもなければ、あなたが気付いていなかったより大きな計画に合わないという理由で 拒否されるリスクがあります。

翻訳

A German translation of this manual (possibly slightly out of date) is available, thanks to O'Reilly, at:

このマニュアルのドイツ語版が(ちょっと古いかもしれませんが)以下のサイトに あります; O'Reilly に感謝します:

  http://www.oreilly.de/catalog/perldbiger/

Some other translations:

その他の翻訳:

 http://cronopio.net/perl/                              - Spanish
 http://member.nifty.ne.jp/hippo2000/dbimemo.htm        - Japanese

トレーニング

References to DBI related training resources. No recommendation implied.

DBIに関連したトレーニングへのリファレンスです。 何ら推奨するわけではありません。

  http://www.treepax.co.uk/
  http://www.keller.com/dbweb/

(If you offer professional DBI related training services, please send me your details so I can add them here.)

(もしあなたがプロフェッショナルな DBI 関係のトレーニングサービスを 提供しているなら、詳細をメールしてもらえればここに追加します。)

その他の関係する作品と Perl モジュール

Apache::DBI by E.Mergl@bawue.de

To be used with the Apache daemon together with an embedded Perl interpreter like mod_perl. Establishes a database connection which remains open for the lifetime of the HTTP daemon. This way the CGI connect and disconnect for every database access becomes superfluous.

mod_perl のような埋め込み型 perl インタプリタとともに Apache デーモンで 使われます。 http デーモンが生きている間ずっと開かれるデータベース接続を確立します。 これにより CGI がデータベースにアクセスする度に接続、切断することが不必要に なります。

SQL Parser

See also the SQL::Statement module, SQL parser and engine.

SQL パーサとエンジンである SQL::Statement モジュールも参照してください。