資料庫非同步訪問Asynchronous

1.建立非同步執行開始

SqlConnectionStringBuilder consetting = new SqlConnectionStringBuilder();

consetting.ConnectionString = ConfigurationManager.ConnectionStrings["Con"].ConnectionString;

 

SqlConnection con = new SqlConnection(consetting.ConnectionString);

con.Open();

 

SqlCommand cmd = con.CreateCommand();

cmd.CommandText = "select @@Version";

cmd.BeginExecuteReader(new AsyncCallback(AsyncExecute), cmd, CommandBehavior.CloseConnection);

2.非同步執行的方法

public void AsyncExecute(IAsyncResult ar)

        {

 

            SqlCommand cmd = (SqlCommand)ar.AsyncState;

            using(cmd.Connection)

            {

                using(cmd)

                {

                    SqlDataReader dr = cmd.EndExecuteReader(ar);

                    string str=string.Empty;

                    if (dr.Read())

                    {

                        str=dr[0].ToString();

                    }

                    label1.BeginInvoke(new DelegateSetlblText(SetText), str);

                }

            }

        }

3.給顯示結果的委託

delegate void DelegateSetlblText(string str);

        public void SetText(string txt)

        {

            label1.Text = txt;

        }