This is the blog to share your views and ideas and opinions of diffrent type of people, on our politics, media movies on each and every thing....

don't forget to comment.....!



(PHP 4 >= 4.3.0, PHP 5)
mysql_real_escape_string -- Escapes special characters in a string for use in a SQL statement


string mysql_real_escape_string ( string unescaped_string [, resource link_identifier] )

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.
The MySQL connection. If the link identifier is not specified, the last link opened by mysql_connect() is assumed. If no such link is found, it will try to create one as if mysql_connect() was called with no arguments. If by chance no connection is found or established, an E_WARNING level warning is generated.

Return Values

Returns the escaped string, or FALSE on error.


Example 1. Simple mysql_real_escape_string() example
// Connect
$link = mysql_connect('mysql_host', 'mysql_user', 'mysql_password')
    OR die(

// Query
$query = sprintf("SELECT * FROM users WHERE user='%s' AND password='%s'",

Example 2. An example SQL Injection Attack
// Query database to check if there are any matching users
$query = "SELECT * FROM users WHERE user='{$_POST['username']}' AND password='{$_POST['password']}'";

// 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.

Example 3. A "Best Practice" query
Using mysql_real_escape_string() around each variable prevents SQL Injection. This example demonstrates the "best practice" method for querying a database, independent of the Magic Quotes setting.
// Quote variable to make safe
function quote_smart($value)
// Stripslashes
if (get_magic_quotes_gpc()) {
$value = stripslashes($value);
// Quote if not a number or a numeric string
if (!is_numeric($value)) {
$value = "'" . mysql_real_escape_string($value) . "'";

// Connect
$link = mysql_connect('mysql_host', 'mysql_user', 'mysql_password')
    OR die(

// Make a safe query
$query = sprintf("SELECT * FROM users WHERE user=%s AND password=%s",

The query will now execute correctly, and SQL Injection attacks will not work.


Note: 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.
Note: 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.
Note: If this function is not used to escape data, the query is vulnerable to SQL Injection Attacks.
Note: mysql_real_escape_string() does not escape % and _. These are wildcards in MySQL if combined with LIKE, GRANT, or REVOKE.


Post a Comment

Bookmark and Share