Winforms 用于订阅SQL表更改的通用实用程序

在互联网上搜索了一段时间后，我发现了这段代码，它会在基于LINQ的数据库更改时触发。它只触发一次，不提及或显示更改/删除/添加的内容，也不显示哪些表被损坏

static class GlobalNotifications
{
    public static event OnChangeEventHandler OnChange;

    public static void InitializeNotifications(string connectString)
    {
        // Initialize notifications
        SqlDependency.Start(connectString);
        // Create and register a new dependency
        SqlDependency dependency = new SqlDependency();
        dependency.OnChange += new OnChangeEventHandler(NotificationCallback);
        System.Runtime.Remoting.Messaging.CallContext.SetData("MS.SqlDependencyCookie", dependency.Id);
    }

    internal static void NotificationCallback(object o, SqlNotificationEventArgs args)
    {
        OnChange.Invoke(o, args);
    }
}

我就是这样使用它的：

public partial class Nawa : Form
{
  public Nawa()
  {
    InitializeComponent();
  }

  private void Nawa_Load(object sender, EventArgs e)
  {
    GlobalNotifications.InitializeNotifications("Server=GENISYSSERVER; Trusted_Connection=no;database=Maple_DBv1; user id=sa; password=Wc123Wc123");
    GlobalNotifications.OnChange += new System.Data.SqlClient.OnChangeEventHandler(GlobalNotifications_OnChange);
  }

  void GlobalNotifications_OnChange(object sender, System.Data.SqlClient.SqlNotificationEventArgs e)
  {
    MessageBox.Show("Test");
  }

  private void button1_Click(object sender, EventArgs e)
  {
    using (DataClasses1DataContext dbcontext = new DataClasses1DataContext("Server=GENISYSSERVER; Trusted_Connection=no;database=Maple_DBv1; user id=sa; password=Wc123Wc123")) {
      OrderFood random = dbcontext.OrderFoods.FirstOrDefault(id => id.ID == 10);

      if (random != null) { 
        if (random.MenuID == 4)
          random.MenuID = 1;
        else
          random.MenuID = 4;

        dbcontext.SubmitChanges();
      }
    }
  }
}

在这方面有人能帮忙吗？如何获得更改内容、更改类型、表更改以及为什么只触发一次的更多详细信息。此外，它如何仅理解LINQ更改？它不会触发直接的变化等

参考：

---

SQLDependency只触发一次，您需要在触发后重新创建依赖项

OnChange事件触发一次，然后被消费，因此您需要在事件触发后再次连接该事件

我手头没有任何C#代码来演示如何处理这个问题，但我相信一些VB.NET应该能够很好地工作，让您能够想出自己的解决方案

Private _permissionsDependency As SqlDependency

Private Sub doSubscribe()
    _permissionsDependency = New SqlDependency(cmd.InnerCommand)
    RemoveHandler _permissionsDependency.OnChange, AddressOf User_OnChange
    AddHandler _permissionsDependency.OnChange, AddressOf User_OnChange
End Sub

Private Sub User_OnChange(ByVal sender As Object, ByVal e As System.Data.SqlClient.SqlNotificationEventArgs)
    If _permissionsDependency IsNot Nothing Then RemoveHandler _permissionsDependency .OnChange, AddressOf User_OnChange

    Select Case e.Info
        Case SqlNotificationInfo.Delete
            RaiseEvent UserDeleted(Me)
        Case SqlNotificationInfo.Update
            populateUser()
            RaiseEvent UserUpdated(Me)
        Case Else
    End Select
End Sub

如您所见，您可以通过查看

e.Info

，了解发生了什么事情（在我的示例中，我只查找删除和更新）