Question

我收到一条我不明白的错误消息。我的MainWindow包含用于打开另一个名为ListMaintenance的窗口的代码：

Private Sub mnuListMaintenance_Click(sender As Object, e As RoutedEventArgs)
    Try
    Dim win As Window = New ListMaintenance
    win.Show()
Catch ex As Exception
    Debug.WriteLine("In Main")
    Debug.WriteLine(ex.ToString)
End Try
End Sub

在ListMaintenance窗口中，我有：

Private Sub winListMaintenance_Loaded(sender As Object, e As RoutedEventArgs) Handles winListMaintenance.Loaded
    Try
        <get data from DB and load dataset tables>
    Catch ex As Exception
        Debug.WriteLine("Loaded")
        Debug.WriteLine(ex.ToString)
    End Try
End Sub

并关闭表单：

Private Sub btnExit_Click(sender As Object, e As RoutedEventArgs) Handles btnExit.Click
    Me.Hide()
End Sub

第一次打开ListMaintenance时，没有错误消息。第二次打开表格，我明白了：

A first chance exception of type 'System.Data.InvalidConstraintException' occurred in System.Data.dll
Loaded
System.Data.InvalidConstraintException: Cannot clear table StandardEntryCategories because ForeignKeyConstraint relSEC_SE enforces constraints and there are child rows in StandardEntries.
at System.Data.ForeignKeyConstraint.CheckCanClearParentTable(DataTable table)
at System.Data.DataTable.Clear(Boolean clearAll)
at System.Data.DataTable.Clear()
at PIM.PIMDataSetTableAdapters.taStandardEntryCategories.Fill(StandardEntryCategoriesDataTable dataTable) in f:\PIM\PIMDataSet.Designer.vb:line 3555
at PIM.ListMaintenance.winListMaintenance_Loaded(Object sender, RoutedEventArgs e) in f:\PIM\ListMaintenance.xaml.vb:line 10

该表确实具有该约束，但我所做的只是打开并关闭表单。没有其他的。如何将新的子行添加到我的表中？

错误消息让我困惑

0 个答案: