config.php

<?php

class DB {

	private static $_MYSQL_HOST="localhost";
	private static $_MYSQL_USER="your_mysql_user";
	private static $_MYSQL_PASS="your_mysql_password";
	private static $_MYSQL_DB="your_mysql_database";
     
    private static $connect  = null;
     
    public function __construct() {
        die('Init function is not allowed');
    }
     
    public static function connect()
    {
       if ( null == self::$connect )
       {     
        try
        {
          self::$connect =  new PDO( "mysql:host=".self::$_MYSQL_HOST.";"."dbname=".self::$_MYSQL_DB, self::$_MYSQL_USER, self::$_MYSQL_PASS); 
        }
        catch(PDOException $exception)
        {
          die($exception->getMessage()); 
        }
       }
       return self::$connect;
    }
     
    public static function disconnect()
    {
        self::$connect = null;
    }

}