vb.net数据库异步操作(二)

 

‘进行详细说明

Imports System.Data.SqlClientImports System.ThreadingModule Program    Sub Main()        ’输入异步操作结果 

        Console.WriteLine("***** Fun with ASNYC Data Readers *****" & vbLf)        ' Create and open a connection that is async-aware.        '创建并打开一个异步连接

         Dim cn As New SqlConnection()        cn.ConnectionString = "Data Source=(local)" & _        ";Integrated Security=SSPI;" & _        "Initial Catalog=newdb;Asynchronous Processing=true"        ‘ Asynchronous Processing=true 这个是必须的

        cn.Open()        ' Create a SQL command object that waits for approx 2 seconds.        '两秒后执行SQL

        Dim strSQL As String = "WaitFor Delay '00:00:02';Select * From tbdata"        Dim myCommand As New SqlCommand(strSQL, cn)        ' Execute the reader on a second thread.         ' 定义异步线程并启用第二线程

        Dim itfAsynch As IAsyncResult        itfAsynch = myCommand.BeginExecuteReader(CommandBehavior.CloseConnection)

        '当线程执行时，执行其它工作        ' Do something while other thread works.         While Not itfAsynch.IsCompleted            Console.WriteLine("Working on main thread...")            'Thread.Sleep(1000)        End While        Console.WriteLine()         ’所有完成后，读出所有数据

        ' All done! Get reader and loop over results.         Dim myDataReader As SqlDataReader = myCommand.EndExecuteReader(itfAsynch)        While myDataReader.Read()            Console.WriteLine("-> 序号: {0}, 临时号: {1}, 车船号: {2}.", _                              myDataReader("Id").ToString().Trim(), _                              myDataReader("序号").ToString().Trim(), _                              myDataReader("车船号").ToString().Trim())        End While        myDataReader.Close()        Console.ReadLine()    End SubEnd Module