public function auth($id, $pass, $login) {

        $data = md5($pass);
        $query = "SELECT  login, pass, id FROM users WHERE login = '$login' AND pass='$data' LIMIT 1";

        $sql = mysql_query($query) or die(mysql_error());

        if (mysql_num_rows($sql) == 1)
        {
            $user = mysql_fetch_row($sql);
            $_SESSION["user_id"] = $user[2];
            header('Location:/index/');
            exit;
        }
        else
        {
        ?>
            Введены неверные данные.
        <?

        }

    }