pg_escape_string

(PHP 4 >= 4.2.0, PHP 5, PHP 7, PHP 8)

pg_escape_string — クエリに使う文字列をエスケープする

説明

pg_escape_string(PgSql\Connection $connection = ?, string $data): string

pg_escape_string() は、データベースへの問い合わせに使う文字列をエスケープします。 PostgreSQL フォーマットにエスケープされた文字列を、クォートなしの形式で返します。 PostgreSQL に使う SQL パラメータをエスケープするときには pg_escape_literal() を使うほうがよいでしょう。 addslashes() を PostgreSQL で使ってはいけません。カラム型が bytea の場合は、代わりに pg_escape_bytea() を使わなければなりません。識別子 (テーブル名やフィールド名など) のエスケープには pg_escape_identifier() を使わなければなりません。

注意:
この関数は、PostgreSQL 7.2 以降が必要です。

パラメータ

connection

PgSql\Connection クラスのインスタンス。 connection が指定されない場合は、デフォルトの接続を使います。デフォルトの接続とは、pg_connect() または pg_pconnect() によって確立された直近の接続です。

警告

PHP 8.1.0 以降では、デフォルトの接続を使うことは推奨されなくなりました。

data

エスケープするテキスト文字列。

戻り値

エスケープされたデータを文字列で返します。

変更履歴

バージョン	説明
8.1.0	`connection` は、PgSql\Connection クラスのインスタンスを期待するようになりました。これより前のバージョンでは、リソースを期待していました。

例

例1 pg_escape_string() の例

<?php 
  // データベースに接続する
  $dbconn = pg_connect('dbname=foo');
  
  // テキストファイルを読み込む（アポストロフィやスラッシュが含まれている）
  $data = file_get_contents('letter.txt');
  
  // テキストデータをエスケープする
  $escaped = pg_escape_string($data);
  
  // それをデータベースに挿入する
  pg_query("INSERT INTO correspondence (name, data) VALUES ('My letter', '{$escaped}')");
?>

参考

pg_escape_bytea() - bytea フィールドに挿入するために文字列をエスケープする

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User Contributed Notes 7 notes

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strata_ranger at hotmail dot com ¶

14 years ago

Forthose curious, the exact escaping performed on the string may vary slightly depending on your database configuration.

For example, if your database's standard_conforming_strings variable is OFF, backslashes are treated as a special character and pg_escape_string() will ensure they are properly escaped.  If this variable is ON, backslashes will be treated as ordinary characters, and pg_escape_string() will leave them as-is.  In either case, the behavior matches the configuration of the database connection.

down

ringerc at ringerc dot id dot au ¶

10 years ago

You should prefer to use pg_query_params, i.e. use parameterized queries, rather than using pg_escape_string. Or use the newer PDO interface with its parameterized query support.

If you must substitute values directly, e.g. in DDL commands that don't support execution as parameterized queries, do so with pg_escape_literal:

http://au1.php.net/manual/en/function.pg-escape-literal.php

Identifiers can't be used as query parameters. Always use pg_escape_identifier for these if they're substituted dynamically:

http://au1.php.net/manual/en/function.pg-escape-identifier.php

You should not need to change text encodings when using this function. Make sure your connection's client_encoding is set to the text encoding used by PHP, and the PostgreSQL client driver will take care of text encodings for you. No explicit utf-8 conversions should be necessary with a correctly set  client_encoding.

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Nathan Bruer ¶

16 years ago

If your database is a UTF-8 database, you will run into problems trying to add some data into your database...



for securty issues and/or compatability you may need to use the: utf_encode() (http://php.net/utf8-encode) function.



for example:

<?php

$my_data = pg_escape_string(utf8_encode($_POST['my_data']));

?>

down

ppp ¶

13 years ago

pg_escape_string() won't cast array arguments to the "Array" string like php usually does; it returns NULL instead. The following statements all evaluate to true:

<?php
$a = array('foo', 'bar');

"$a" == 'Array';
(string)$a == 'Array';
$a . '' == 'Array';

is_null(pg_escape_string($a));
?>

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johniskew2 at yahoo dot com ¶

18 years ago

For those who escape their single quotes with a backslash (ie \') instead of two single quotes in a row (ie '') there has recently been a SERIOUS sql injection vulnerability that can be employed taking advantage of your chosen escaping method.  More info here: http://www.postgresql.org/docs/techdocs.50
Even after the postgre update, you may still be limited to what you can do with your queries if you still insist on backslash escaping. It's a lesson to always use the PHP functions to do proper escaping instead of adhoc addslashes or magic quotes escaping.

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meng ¶

18 years ago

Since php 5.1 the new function pg_query_params() was introduced. With this function you can use bind variables and don't have to escape strings. If you can use it, do so. If unsure why, check the changelog for Postgres 8.0.8.

down

otix ¶

18 years ago

Creating a double-tick is just fine. It works the same as the backslash-tick syntax. From the PostgreSQL docs:

The fact that string constants are bound by single quotes presents an obvious semantic problem, however, in that if the sequence itself contains a single quote, the literal bounds of the constant are made ambiguous. To escape (make literal) a single quote within the string, you may type two adjacent single quotes. The parser will interpret the two adjacent single quotes within the string constant as a single, literal single quote. PostgreSQL will also allow single quotes to be embedded by using a C-style backslash.

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