Question

如何使用mysql query执行2 ThreadingTimer？我希望db和2nd计时器中的第一个计时器更新数据计算更新的数据量，并以windows格式显示在标签中。这是我的代码，

   void PrepareTimers(List<int> _dataValues)
   {
        foreach (int dataValue in _dataValues)
        {
            timer = new ThreadingTimer (new TimerCallback(TimerAction), dataValue, 0, 2000);
            timer1 = new ThreadingTimer(new TimerCallback(TimerAction1), dataValue, 0, 2000);

            //Console.WriteLine("Timer " + dataValue + " created.");


        }
    }
    void TimerAction(object flag)
    {
        //Console.WriteLine("Timer start "+ flag.ToString());
        string myconstring = "SERVER=localhost;" + "DATABASE=alicosms;" + "UID=root;" + "PASSWORD=;";
        MySqlConnection mycon = new MySqlConnection(myconstring);
        string u = "UPDATED";
        mycon.Open();
        //Console.WriteLine("Timer " + flag.ToString() + " : " + "UPDATE sms_data_bankasia set flag= @flag * 2 , sendingstatus = '" + u + "' WHERE flag = " + flag.ToString() + "  LIMIT 1");
        MySqlCommand cmd = new MySqlCommand("UPDATE sms_data_bankasia set flag= @flag * 2 , sendingstatus = '" + u + "' WHERE flag = " + flag.ToString() + " LIMIT 1", mycon);
        MySqlParameter param = new MySqlParameter();
        param.ParameterName = "@flag";
        param.Value = flag;
        cmd.Parameters.Add(param);
        cmd.ExecuteNonQuery();
        mycon.Close();                                  
    }

    void TimerAction1(object flag)
    {
        string myconstring = "SERVER=localhost;" + "DATABASE=alicosms;" + "UID=root;" + "PASSWORD=;";
        MySqlConnection mycon = new MySqlConnection(myconstring);
        string sql = "SELECT count(flag) FROM sms_data_bankasia where sendingstatus='UPDATED' group by flag";
        MySqlCommand comd = mycon.CreateCommand();
        comd.CommandText = sql;
        mycon.Open();
        MySqlDataReader dtr = comd.ExecuteReader();
        try
        {
            while (dtr.Read())
            {
                dict[timer] = label;
                dict[timer].Text = dtr[0].ToString() + " program Updated";
            }
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.Message);
        }
        mycon.Close();
    }

提供error,"cross thread operation not valid".我该怎么办？有什么好建议吗？

Answer 1

在Windows窗体中，除了UI线程之外，您无法在UI中执行任何其他操作。您的计时器正在单独的线程上运行您的代码。

您可以尝试使用System.Windows.Forms.Timer，因为它会将事件处理编组回给您的UI线程。

Answer 2

Here you can read about the solution

只是为了测试它是否修复了你的问题，试着用这样的代码包装你的MessageBox调用：

public delegate void StringDelegate(string message);

private void ShowMessageBox( string message )
{
    if (this.InvokeRequired)
    {
        this.Invoke( new StringDelegate( ShowMessageBox, new object[] { message } ));
        return;
    }

    MessageBox.Show( message );
}

这部分是从记忆中写的，所以它可能会有所不同。

在C＃中使用timer执行2个MySql查询

2 个答案: