在打开连接之前如何检查我的 SqlConnection 状态？答案

【问题标题】：How do I check my SqlConnection state before open connection?在打开连接之前如何检查我的 SqlConnection 状态？
【发布时间】：2014-01-24 09:32:13
【问题描述】：

如何检查mysqlconnection 的连接是否已打开？我希望如果连接已经打开，则不需要再次打开它：

 Connection = New MySqlConnection()
 Connection.ConnectionString = ConfigurationManager.ConnectionStrings("DbConncetionString").ConnectionString
 Connection.Open()
 SQL = "SELECT * from TBL_PARKERS where id=" & encode(Request.Cookies("parker").Values("id")) & ""
 Dim Query As MySqlCommand = New MySqlCommand(SQL, Connection)
 'Here  i want to check connection is open or close 
 Connection.Open()

【问题讨论】：

打开两次会不会有什么不好的事情发生？如果“不”，那就不要打扰。

标签： asp.net vb.net sqlconnection

【解决方案1】：

鉴于MySqlConnection 派生自DbConnection，您可以检查State 属性，例如

Connection.State == ConnectionState.Open

【讨论】：

【解决方案2】：

您可以使用此功能进行测试连接。

Public Function TestConn(ByVal server As String) As Boolean

    Using tcpSocket As New System.Net.Sockets.TcpClient
        Try
            Dim async As IAsyncResult = tcpSocket.BeginConnect(server, 1433, Nothing, Nothing)
            Dim startTime As DateTime = DateTime.Now

            Do
                System.Threading.Thread.Sleep(500)
                If (async.IsCompleted) Then
                    Exit Do
                End If
            Loop While (DateTime.Now.Subtract(startTime).TotalSeconds < 5)

            If (async.IsCompleted) Then
                tcpSocket.EndConnect(async)
                Return True
            End If
            tcpSocket.Close()

            If (async.IsCompleted = False) Then
                Return False
            End If

        Catch ex As Exception

            My.Application.Log.WriteEntry("[" & DateTime.Now & "] - " & ex.Source & ": " & ex.Message)


        End Try
    End Using
End Function

记住打开 TCP/IP 端口号 1433。

问候！

【讨论】：