ADO.NET最佳实践（中）[13]

  conn.open();

  using (sqldatareader dr = cmd.executereader())

  {

    while (dr.read())

      console.writeline("{0}\t{1}", dr.getstring(0), dr.getstring(1));

  }

}

            using声明在visual basic.net中不可用。

        xii．避免访问oledbconnection.state属性

            如果你需要经常检查state属性，最好在oledbconnection上监听statechange事件。下面的代码演示当oledbconnection.state发生变化时使用statechange向控制台发送一条消息：

‘visual basic

addhandler nwindconn.statechange, new statechangeeventhandler(addressof onstatechange)

protected shared sub onstatechange(sender as object, args as statechangeeventargs)

  console.writeline("the current connection state has changed from {0} to {1}.", _

                    args.originalstate, args.currentstate)

end sub

‘c#

nwindconn.statechange  += new statechangeeventhandler(onstatechange);