(PHP 4 >= 4.3.0, PHP 5)
mysql_real_escape_string — Escapes special characters in a string for use in an SQL statement
Escapes special characters in the unescaped_string, taking into account the current character set of the connection so that it is safe to place it in a mysql_query(). If binary data is to be inserted, this function must be used.
mysql_real_escape_string() calls MySQL's library function mysql_real_escape_string, which prepends backslashes to the following characters: \x00, \n, \r, \, ', " and \x1a.
This function must always (with few exceptions) be used to make data safe before sending a query to MySQL.
The string that is to be escaped.
MySQL bağlantısı. Eğer bağlantı belirteci belirtilmemişse mysql_connect() tarafından açılan son bağlantı kullanılmaya çalışılır. Eğer böyle bir bağlantı yoksa mysql_connect() değiştirgesiz olarak çağrılmış gibi bir bağlantı oluşturmaya çalışır. Hiçbir bağlantı yoksa ve yenisi de kurulamazsa E_WARNING seviyesinde bir hata üretilir.
Returns the escaped string, or FALSE on error.
Örnek 1 Simple mysql_real_escape_string() example
<?php
// Connect
$link = mysql_connect('mysql_host', 'mysql_user', 'mysql_password')
OR die(mysql_error());
// Query
$query = sprintf("SELECT * FROM users WHERE user='%s' AND password='%s'",
mysql_real_escape_string($user),
mysql_real_escape_string($password));
?>
Örnek 2 An example SQL Injection Attack
<?php
// Query database to check if there are any matching users
$query = "SELECT * FROM users WHERE user='{$_POST['username']}' AND password='{$_POST['password']}'";
mysql_query($query);
// We didn't check $_POST['password'], it could be anything the user wanted! For example:
$_POST['username'] = 'aidan';
$_POST['password'] = "' OR ''='";
// This means the query sent to MySQL would be:
echo $query;
?>
The query sent to MySQL:
SELECT * FROM users WHERE user='aidan' AND password='' OR ''=''
This would allow anyone to log in without a valid password.
Bilginize:
A MySQL connection is required before using mysql_real_escape_string() otherwise an error of level E_WARNING is generated, and FALSE is returned. If link_identifier isn't defined, the last MySQL connection is used.
Bilginize:
If magic_quotes_gpc is enabled, first apply stripslashes() to the data. Using this function on data which has already been escaped will escape the data twice.
Bilginize:
If this function is not used to escape data, the query is vulnerable to SQL Injection Attacks.
Bilginize: mysql_real_escape_string() does not escape % and _. These are wildcards in MySQL if combined with LIKE, GRANT, or REVOKE.