主题：子表按条件赋值给父表

下面是代码，但搞了一个晚上还是不行，望老师指点

代码位置：子表的DataColChanged

If e.DataCol.Name = "产地" Then
    Dim pdr As DataRow = e.DataRow.GetParentRow("订单")
    Dim fdr As DataRow = e.DataTable.Find("[订单号]='" & e.DataRow("订单号") & "'","_Sortkey")
    'Dim fdr2 As DataRow = e.DataTable.Find("[产地]='上海'","_Sortkey")
    If pdr IsNot Nothing Then
        If fdr IsNot Nothing Then
            Dim drs As List(Of DataRow) = DataTables("订单明细").Select("[订单号]='" & e.DataRow("订单号") & "'")
            ' For n As Integer = 0 To drs.Count - 1 '遍历所有行
            For Each dr As DataRow In drs
                If dr("产地") ="上海" Then
                    pdr("地址") ="上海"
                Else
                    pdr("地址") = fdr("产地")
                    'pdr("地址") = Nothing
                End If
            Next
        End If
    End If
End If