mysql_real_escape_string Escapes special characters in a string for use in a SQL statement stringmysql_real_escape_string stringunescaped_string resourcelink_identifier unescaped_string The string to escape link_identifier (optional) The mysql connection resource This function will escape 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_escape_string, which prepends backslashes to the following characters: NULL, \x00, \n, \r, \, ', " and \x1a. ]]> This function must always (with few exceptions) be used to make data safe before sending a query to MySQL. 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. If this function is not used to escape data, the query is vulnerable to SQL Injection Attacks. ]]> The query sent to MySQL: This would allow anyone to log in without a valid password. 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. mysql_real_escape_string does not escape % and _. These are wildcards in MySQL if combined with LIKE, GRANT, or REVOKE. See also mysql_client_encoding, addslashes, stripslashes, the magic_quotes_gpc, and the magic_quotes_runtime directive.