Question

我试图在将新数据添加到数据库时调用一个函数。

NpgsqlConnection connListenRun = new NpgsqlConnection("Server=main;Port=5432;Database=netdb;UserId=postgres;Password=password;");
        try
        {
            connListenRun.Open();
            NpgsqlCommand cmd = new NpgsqlCommand("listen RunLogClient;", connListenRun);
            cmd.ExecuteNonQuery();
            connListenRun.Notification += new NotificationEventHandler(RunFinishNotification);
        }
        catch (NpgsqlException ex)
        {
            MessageBox.Show(ex.ToString());
        }
        finally
        {
            //connListen.Close();
        }

private void RunFinishNotification(object sender, NpgsqlNotificationEventArgs e)
    {
        MessageBox.Show("Data!");
    }

但是，添加新数据时我的消息框没有显示。在使用相同触发函数的另一个程序上具有“ SyncNotification = true;”在conListenRun的末尾。

NpgsqlConnection connListenRun = new NpgsqlConnection("Server=main;Port=5432;Database=netdb;UserId=postgres;Password=password;SyncNotification=true;");

但是，当我输入“ SyncNotification = true;”时在陈述中我得到这个错误：

：'不支持关键字：同步通知参数名称：关键字'

我在做什么错了？

谢谢

Answer 1

我正在使用NPGSQL的最新版本3.6.2（我认为），而其他项目正在使用2.11.96版本。由于使用旧版本，因此该程序可以运行。我猜较新的NPGSQL使用了不同的方式来执行触发函数。

Answer 2

具有npgsql.dll版本的示例代码
知道这适用于3.2.6.0或从Postgres 10起的版本（这可能意味着从ngpsql.dll v3.0起）。

public static void Main(string[] args)   
{
    bool flag = true;
    string server = "127.0.0.1";
    string port = "5432";
    string database = "postgres";
    string uid = "postgres";
    string password = "postgres";
    string connStr;

    // the connection string
    connStr = $"SERVER = {server}; Port = {port};  DATABASE = {database}; User Id = 
    {uid}; PASSWORD = {password};"; 
    NpgsqlConnection notificationConnection;
    NpgsqlConnectionStringBuilder csb = new NpgsqlConnectionStringBuilder(connStr);


    try
    {
        notificationConnection = new NpgsqlConnection(connStr);
        notificationConnection.Open();
        if (notificationConnection.State != System.Data.ConnectionState.Open)
        {
            WriteLine("Connection to database failed");
            return;
        }

        using (NpgsqlCommand cmd = new NpgsqlCommand($"LISTEN {notificationName}", 
               notificationConnection))
        {
            cmd.ExecuteNonQuery();
        }

        notificationConnection.Notification += PostgresNotification;
        notificationConnection.WaitAsync();
    }   
    catch(Exception ex)
   {
       WriteLine($"Exception thrown with message : {ex.Message}");
       return;
   }

   //  wait forever, press enter key to exit program  
   ReadLine();

   // stop the db notifcation
   notificationConnection.Notification -= PostgresNotification;
   using (var command = new NpgsqlCommand($"unlisten {notificationName}", 
      notificationConnection))
   {
       command.ExecuteNonQuery();
   }
       notificationConnection.Close();
}






//  the callback method that handles notification
static void PostgresNotification(object sender, NpgsqlNotificationEventArgs e)
{
     WriteLine("Notification Received");
}

Answer 3

您缺少connconnListenRun.WaitAsync();或connconnListenRun.Wait();

Postgres C＃触发函数

3 个答案: