(PHP 4 >= 4.3.0, PHP 5)mysql_real_escape_string -- Escapes special characters in a string for use in a SQL statement
Escapes special characters in the
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.
Example 1. Simple mysql_real_escape_string() example
Example 2. An example SQL Injection Attack
The query sent to MySQL:
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.
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_identifierisn't defined, the last MySQL connection is used.
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.
|The magic_quotes_gpc directive|
|The magic_quotes_runtime directive|