Question

I ve written a console app in VB. 该网络从事一些数据库工作,并出现奇怪的运行时间错误。

The main Code:

Sub Main(ByVal args() As String)
        Try
            user = args(0)
            batchID = args(1)

            GetBatchRevision()
             batchRev = 1

            Dim getTestScripts As SqlCommand = New SqlCommand("GetTestScriptsInTestBatch", cs)
            getTestScripts.CommandType = CommandType.StoredProcedure

            Dim batchIDParam As SqlParameter = getTestScripts.Parameters.Add("@batchID", SqlDbType.Int, 4)
            Dim batchRevParam As SqlParameter = getTestScripts.Parameters.Add("@batchRev", SqlDbType.Int, 4)

             batchIDParam.Value = 1
             batchRevParam.Value = 1
            batchIDParam.Value = batchID
            batchRevParam.Value = batchRev

            Console.WriteLine(batchID & " " & batchRev)
            Console.WriteLine(cs.State)
            Console.ReadLine()

            Using cs
                cs.Open()
                Dim reader As SqlDataReader = getTestScripts.ExecuteReader(CommandBehavior.CloseConnection)

                While reader.Read()
                    Console.WriteLine("Executing Test Script " & reader("ScriptID").ToString() & " Revision " & reader("ScriptRev").ToString)
                End While

                Console.ReadLine()
            End Using

        Catch ex As Exception
        End Try
    End Sub

GetBatchRevision:

Private Sub GetBatchRevision()
    Using cs
        Dim GetNewestRev As New SqlCommand("SELECT Max(BatchRev) FROM TestBatch WHERE BatchID=" & batchID, cs)
        cs.Open()
        Dim reader As SqlDataReader = GetNewestRev.ExecuteReader(CommandBehavior.CloseConnection)
        reader.Read()

        If Not IsDBNull(reader(0)) Then
            batchRev = reader(0).ToString()
        End If
    End Using

End Sub

<代码>batchRev和batchID均为该模块内的全球变量。

突然:

The app prints out "1" (user input), "1" (database result), "0" (enum of Closed connection)
When I press Enter to get past the first Console.ReadLine(), the app simply closes out.

如果我发表以下意见:GetBatchRevision,并直接设定batchRev = 1,则我得出上述结果,以及“Executing Test 1 Revision 52”,“Executing Test cast 2 Revision 66”,这些结果是所储存程序的结果。《在试验中的试验》()。

全球变化宣言如下:

<条码> ID As String

<条码> Rev As String

任何想法,为什么)导致该机坠毁? 它本身(删除该法典中储存的部分)只执行罚款。我最初的猜测是,存在着一种hang然的联系,但结束一个“使用”的区块应该是关闭King的连接以及与这种连接相关的任何公开读者(如前文所述,国家回归0)。

Answer 1

参看<代码>cs也是全球变量。这是一个坏的想法。当你每次重新使用新链接时,网络数据存取会更好。也许,你会这样做,但你会重建一些坏习惯。相反,把你的联系作为全球变量加以载荷,并在建立你的联系时加以利用。

其次,没有理由讨论全球变量的<代码>GetBatchRevision(。它是否接受论点,而是结果。当然,我可以忽略 s子注射问题,因为你把bat子混为一谈,直到你扼杀为止。在确定这些错误后,将职能的新版本改为:

Private Function GetBatchRevision(ByVal BatchID As String) As String
    Using cn As New SqlConnection(cs), _
          GetNewestRev As New SqlCommand("SELECT Max(BatchRev) FROM TestBatch WHERE BatchID= @BatchID", cn)

        GetNewestRev.Parameters.Add("@Batch", SqlDbType.Int).Value = Convert.ToInt32(BatchId)

        cn.Open()
        Return GetNewestRev.ExecuteScalar().ToString() 
    End Using

End Function

如果你把BatchRev和BatchID当作 in,而不是在内部加以扼杀,这甚至会更好。

Answer 2

你的问题是:

 reader.Read()

 If Not IsDBNull(reader(0)) Then

<代码>reader.Read(>> 或许会退回不实;然而,你试图查阅reader(0)。 !!

您应将其改为:

IF reader.Read() AndAlso Not IsDBNull(reader(0)) Then
       etc
End If

友情链接