public function __construct()
    {
        $this->pdo = new PDO('mysql:host=' . HOST . ';dbname='.DB, USER, PASS);

        try
        {
            $this->pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
        }
        catch(PDOException $e)
        {
            return $e->getMessage();
        }
        return null;
    }