如果post cardid相同，如何更新和插入

Question

如果后卡号相同，如何更新和插入

    $stmt = $conn->prepare("INSERT INTO `attendance`(`cardid`, `time_in`, `time_out`, `date`, `status`) VALUES ('$cardid', '$time_now','$time_now', '$date_now', '1')");

    $stmt->execute();

    echo "success";
}