using System;using System.Collections.Generic;using System.Text;using System.Data.SqlClient;using System.Data;using System.Windows.Forms;namespace WindowsApplication2{ public class AsyncCallBackOpeartion {  private static DataGridView dataGridView;  public static void AsyncCallBack(string connectionString, string sql, DataGridView dgv)  {   dataGridView = dgv;   connectionString += ";Asynchronous Processing=true";   SqlConnection conn = new SqlConnection(connectionString);   SqlCommand command = new SqlCommand(sql, conn);   conn.Open();   command.BeginExecuteReader(new AsyncCallback(AsyncCallBack), command);  }  static void AsyncCallBack(IAsyncResult ar)  {   if (ar.IsCompleted)   {    SqlCommand com = (SqlCommand)ar.AsyncState;    SqlDataReader dr = com.EndExecuteReader(ar);    DataTable dt = new DataTable();    dt.Load(dr);    dr.Close();    if (dataGridView.InvokeRequired)    {     updateDG ur = new updateDG(dataBin);     dataGridView.Invoke(ur, dt);    }   }  }  delegate void updateDG(DataTable dt);  public static void dataBin(DataTable dt)  {   dataGridView.DataSource = dt;  } }}