Simon's MySQL

Deprecated — Use Super-MySQL

smysql-old-1.php is for PHP 5.3 and earlier versions (required [MySQL library](http://php.net/manual/en/book.mysql.php)). 
smysql.php is for PHP 5.4 and later versions (required [MySQLi library](http://php.net/manual/en/book.mysqli.php)).
Here is documentation.