调用未定义的函数mysql_error（）

Question

我在第die(mysql_error());行收到了错误，我应该在这里修理。     

        $conn=new PDO('mysql:host=localhost; dbname=xxx', 'xxx', 'xxx') or die(mysql_error());

        if(isset($_GET['user_id']) && !empty($_GET['user_id']))
        {
            $user_id = $_GET['user_id'];
            $stmt = $conn->prepare('SELECT * FROM member WHERE user_id =:user_id');
            $stmt->execute(array(':user_id'=>$user_id));
            $row = $stmt->fetch(PDO::FETCH_ASSOC);
            extract($row);
        }
        else
        {
            header("Location: reg1.php");
        }

    if(isset($_POST['submit'])!=""){

        $nama = $_POST['nama'];
        $username = $_POST['username'];
        $tanggal_join = date("Y-m-d H:i:s");
        $email = $_POST['email'];
        $passwd = $_POST['passwd'];
        $kode_pos = $_POST['kode_pos'];
        $telp = $_POST['telp'];
        $kota = $_POST['kota'];
        $sponsor_username2 = $_POST['sponsor_username2']; 
        $sponsor_username3 = $_POST['sponsor_username3'];
        $sponsor_username4 = $_POST['sponsor_username4'];
        $sponsor_username5 = $_POST['sponsor_username5'];
        $sponsor_username6 = $_POST['sponsor_username6'];
        $sponsor_username7 = $_POST['sponsor_username7'];
        $sponsor_username8 = $_POST['sponsor_username8'];
        $sponsor_username9 = $_POST['sponsor_username9'];
        $sponsor_username10 = $_POST['sponsor_username10'];
        $bank_atasnama = $_POST['bank_atasnama'];
        $bank_nama = $_POST['bank_nama']; 
        $bank_rekening = $_POST['bank_rekening']; 

    $query=$conn->query("INSERT INTO member(username, nama, tanggal_join, email, passwd, kode_pos, telp, kota, sponsor_username2, sponsor_username3, sponsor_username4, sponsor_username5, sponsor_username6, sponsor_username7, sponsor_username8, sponsor_username9, sponsor_username10, bank_atasnama, bank_nama, bank_rekening )VALUES('$username', $nama', '$tanggal_join', '$email', '$passwd', '$kode_pos', '$telp', '$kota', '$sponsor_username2', '$sponsor_username3', '$sponsor_username4', '$sponsor_username5', '$sponsor_username6', '$sponsor_username7', '$sponsor_username8', '$sponsor_username9', '$sponsor_username10', '$bank_atasnama', '$bank_nama', '$bank_rekening')");
    if($query){
    header("location:reg1.php");
        }
    else{
    die(mysql_error());
        }
    }
    ?>