php 5.6 sürümünde çalışıyorsa eğer, mysql kullanamaz.

Warning
This extension was deprecated in PHP 5.5.0, and it was removed in PHP 7.0.0. Instead, the MySQLi or PDO_MySQL extension should be used. See also MySQL: choosing an API guide and related FAQ for more information. Alternatives to this function include:

mysqli_connect()
PDO::__construct()

Kaynak: https://www.php.net/manual/en/function.mysql-connect.php