Question

我在.net 4.5.2上运行了一个vb.net wpf应用程序。此应用程序通过读写功能连接到Access 2013数据库（.accdb）（一种自定义构建的实体框架，在开始时读取，最后写入/更新/删除）。

我为每个表连续多次读取和多次写入。他们都在不说数据库被锁定的情况下工作。

我用这个函数创建了我的connectionstring：

Function newconnectionstring() As System.Data.OleDb.OleDbConnection
    newconnectionstring = New System.Data.OleDb.OleDbConnection("myconnectionstring")
End Function

这是我最后的读写功能：

READ（似乎没有锁定数据库）

Sub ImportTechnicalLabels()
    TechnicalLabels = New Dictionary(Of String, TechnicalLabel)(StringComparer.OrdinalIgnoreCase)
    Dim accessconnection As System.Data.OleDb.OleDbConnection
    accessconnection = newconnectionstring()
    accessconnection.Open()
    Dim sSQL As String = "SELECT * FROM TechnicalLabels"
    Dim objCmd As New OleDbCommand(sSQL, accessconnection)
    Dim reader As OleDbDataReader
    Dim readerTechnicalLabel As TechnicalLabel

    reader = objCmd.ExecuteReader

    While reader.Read
        readerTechnicalLabel = New TechnicalLabel
        With readerTechnicalLabel
            .UpdateStatus = 0
            .TechnicallabelID = reader.Item("TechnicallabelID").ToString
        End With
        TechnicalLabels.Add(readerTechnicalLabel.TechnicalLabelID, readerTechnicalLabel)
    End While

    reader.Close()
    accessconnection.Close()
    accessconnection = Nothing
    reader = Nothing
End Sub

WRITE（保持数据库锁定但允许其他表上的写入继续）

Sub UpdateConcessionlines()
    Dim accessconnection As System.Data.OleDb.OleDbConnection
    accessconnection = newconnectionstring()
    accessconnection.Open()
    Dim updatesql As String = "UPDATE Concessionlines SET ConcessionLineID=@ConlID, ConcessionID=@ConID, Defect = @Def, MeasureID=@MeID, Comment =@Com, Numberitembtd  = @Nbibt, LineTechnicalDecisionID = @LTechID WHERE (ConcessionLineID = @ConlID);"
    Dim updatecmd As OleDbCommand
    Dim addsql As String = "INSERT INTO Concessionlines VALUES (@ConlID, @ConID, @Def, @MeID, @Com, @Nbibt, @LTechID);"
    Dim addcmd As OleDbCommand
    Dim deletesql As String = "DELETE FROM Concessionlines WHERE ConcessionLineID = @ConlID"
    Dim deletecmd As OleDbCommand

    For Each item In (From Conlis In Concessionlines.Values Where Conlis.UpdateStatus = 1 Select Conlis).ToList
        updatecmd = New OleDbCommand(updatesql, accessconnection)
        With updatecmd
            If Not item.ConcessionLineID = Nothing Then
                .Parameters.AddWithValue("@ConlID", item.ConcessionLineID)
            Else
                .Parameters.AddWithValue("@ConlID", DBNull.Value)
            End If
            '... and so on
        End With
        updatecmd.ExecuteNonQuery()
    Next item

    For Each item In (From Conlis In Concessionlines.Values Where Conlis.UpdateStatus = 2 Select Conlis).ToList
        addcmd = New OleDbCommand(addsql, accessconnection)
        With addcmd
            If Not item.ConcessionLineID = Nothing Then
                .Parameters.AddWithValue("@ConlID", item.ConcessionLineID)
            Else
                .Parameters.AddWithValue("@ConlID", DBNull.Value)
            End If
            '... and so on
        End With
        addcmd.ExecuteNonQuery()
    Next item

    For Each item In (From Conlis In Concessionlines.Values Where Conlis.UpdateStatus = 3 Select Conlis).ToList
        deletecmd = New OleDbCommand(deletesql, accessconnection)
        With deletecmd
            If Not item.ConcessionLineID = Nothing Then
                .Parameters.AddWithValue("@ConlID", item.ConcessionLineID)
            Else
                .Parameters.AddWithValue("@ConlID", DBNull.Value)
            End If
        End With
        deletecmd.ExecuteNonQuery()
    Next item

    accessconnection.Close()
    accessconnection = Nothing
End Sub

但最后，数据库被锁定，我无法再次启动整个过程。如果我尝试手动删除accdbl文件，我会收到以下消息：

由于此文件已打开，因此无法完成此操作 WpfApplication1。

我必须完全关闭我的应用程序才能重新开始。

知道为什么我的访问数据库保持锁定状态？或者也许任何想法在不知道是什么导致锁定的情况下释放数据库？谢谢你的帮助。

更新

我把问题缩小了。显然问题来自删除操作。我现在已经以不同的方式组织了我的代码，所以我还没有解决这个问题。但我想的是问题可能来自我为某些访问关系选择的级联删除选项。待验证......

为什么即使在连接关闭后，我的wpf vb.net应用程序也会锁定我的Access数据库？

0 个答案: