主题：价格为数字0，汇总表为空

If e.DataCol.Name = "零件图号" Then
    Dim ys As String() = {2015, 2016,2017}
    For Each y As String In ys
        If e.NewValue Is Nothing Then
            e.DataRow("年" & y & "_A点_供应商简称") = Nothing
            e.DataRow("年" & y & "_A点_含税单价") = Nothing
            e.DataRow("年" & y & "_B点_供应商简称") = Nothing
            e.DataRow("年" & y & "_B点_含税单价") = Nothing
        Else
            Dim dr As DataRow
            dr = DataTables("价格表" & y).Find("[零件图号] = '" &   e.NewValue & "'")
            If dr IsNot Nothing
                e.DataRow("年" & y & "_A点_供应商简称") = dr("A点_供应商简称")
                               e.DataRow("年" & y & "_A点_含税单价") = IIF(dr("A点_含税单价_更新后")=0, Nothing,dr("A点_含税单价_更新后"))
                e.DataRow("年" & y & "_B点_供应商简称") = dr("B点_供应商简称")
                               e.DataRow("年" & y & "_B点_含税单价") = IIF(dr("B点_含税单价_更新后")=0, Nothing,dr("B点_含税单价_更新后"))
            End If
        End If
    Next
End If

通过上面的程序，把价格表{2015, 2016,2017}汇总到“价格汇总表”时，怎么价格表里面为数字0的，汇总表为空呢？怎么修改程序？