PHP 8.4.0 RC3 available for testing

    pg_escape_string

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

    pg_escape_string — Escape a string for query

    Description

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

    pg_escape_string() escapes a string for querying the database. It returns an escaped string in the PostgreSQL format without quotes. pg_escape_literal() is more preferred way to escape SQL parameters for PostgreSQL. addslashes() must not be used with PostgreSQL. If the type of the column is bytea, pg_escape_bytea() must be used instead. pg_escape_identifier() must be used to escape identifiers (e.g. table names, field names)

    Note:

    This function requires PostgreSQL 7.2 or later.

    Parameters

    connection

    An PgSql\Connection instance. When connection is unspecified, the default connection is used. The default connection is the last connection made by pg_connect() or pg_pconnect().

    Warning

    As of PHP 8.1.0, using the default connection is deprecated.

    data

    A string containing text to be escaped.

    Return Values

    A string containing the escaped data.

    Changelog

    Version Description
    8.1.0 The connection parameter expects an PgSql\Connection instance now; previously, a resource was expected.

    Examples

    Example #1 pg_escape_string() example

    <?php
    // Connect to the database
    $dbconn = pg_connect('dbname=foo');

    // Read in a text file (containing apostrophes and backslashes)
    $data = file_get_contents('letter.txt');

    // Escape the text data
    $escaped = pg_escape_string($data);

    // Insert it into the database
    pg_query("INSERT INTO correspondence (name, data) VALUES ('My letter', '{$escaped}')");
    ?>

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    User Contributed Notes 7 notes

    up
    5
    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.
    up
    3
    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.
    up
    2
    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']));
    ?>
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    0
    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));
    ?>
    up
    0
    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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    0
    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.
    up
    0
    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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