(PHP 4 >= 4.3.0, PHP 5)
mysql_real_escape_string — Escapes special characters in a string for use in an SQL statement
Această extensie a devenit învechită în PHP 5.5.0 și a fost eliminată în PHP 7.0.0. În locul ei trebuie utilizată extensia MySQLi sau PDO_MySQL. Accesați de asemenea ghidul MySQL: selectarea unei API și FAQ asociat pentru informații suplimentare. Variante alternative pentru această funcție includ:
$unescaped_string
[, resource $link_identifier = NULL
] ) : string
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 character set must be set either at the server level, or with the API function mysql_set_charset() for it to affect mysql_real_escape_string(). See the concepts section on character sets for more information.
unescaped_stringThe string that is to be escaped.
link_identifier
Conexiunea MySQL. Dacă identificatorul
legăturii nu este specificat, se presupune că este ultima legătură deschisă cu
ajutorul mysql_connect(). Dacă nu este găsită nici o astfel
de legătură, se va încerca crearea uneia prin apelul mysql_connect
() fără argumente. În caz că nici o conexiune nu este găsită sau
stabilită, se va genera o eroare de nivelul E_WARNING.
Returns the escaped string, or FALSE on error.
Executing this function without a MySQL connection present will
also emit E_WARNING level PHP errors. Only
execute this function with a valid MySQL connection present.
Example #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));
?>
Example #2 mysql_real_escape_string() requires a connection example
This example demonstrates what happens if a MySQL connection is not present when calling this function.
<?php
// We have not connected to MySQL
$lastname = "O'Reilly";
$_lastname = mysql_real_escape_string($lastname);
$query = "SELECT * FROM actors WHERE last_name = '$_lastname'";
var_dump($_lastname);
var_dump($query);
?>
Exemplul de mai sus va afișa ceva similar cu:
Warning: mysql_real_escape_string(): No such file or directory in /this/test/script.php on line 5 Warning: mysql_real_escape_string(): A link to the server could not be established in /this/test/script.php on line 5 bool(false) string(41) "SELECT * FROM actors WHERE last_name = ''"
Example #3 An example SQL Injection Attack
<?php
// We didn't check $_POST['password'], it could be anything the user wanted! For example:
$_POST['username'] = 'aidan';
$_POST['password'] = "' OR ''='";
// 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);
// 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.
Notă:
A MySQL connection is required before using mysql_real_escape_string() otherwise an error of level
E_WARNINGis generated, andFALSEis returned. Iflink_identifierisn't defined, the last MySQL connection is used.
Notă:
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.
Notă:
If this function is not used to escape data, the query is vulnerable to SQL Injection Attacks.
Notă: mysql_real_escape_string() does not escape % and _. These are wildcards in MySQL if combined with LIKE, GRANT, or REVOKE.