Code Refactoring - from MySQL Extension to PDO Extension

[devasia2112]

The class located in: /includes/Sql/sql.class.php should use another extension to connect to the MySQL. It will be completely replaced with PDO very soon.

From PHP website:
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_query()
PDO::query()