以下是图例中【转换】按钮的代码，将用料表的数据复制到BOM。每次复制时都要新增行。现在需要【修改】按钮的代码，取消转换勾选，不新增行，只是对现有数据进行修改。

\'DataTables("产品BOM").DataRows.Clear
Dim drs As List(Of DataRow) = DataTables("用料").Select("[导体] Is Not Null And [转换] = False")
If drs.Count = 0 Then
    MessageBox.Show("没有新数据!")
    Return
Else
\'生成BOM
    Tables("BOM").StopRedraw
    For Each dr As DataRow In drs
        For Each dc As DataCol In DataTables("用料").DataCols
            Select Case dc.Name
                Case "产品分类","型号","规格","转换"
                Case Else
                    If dr.IsNull(dc.Name) = False Then
                        Dim n As Row = Tables("BOM").Addnew
                        n("产品分类") = dr("产品分类")
                        n("型号") = dr("型号")
                        n("规格") = dr("规格")
                        n("材料分类") = dc.Name
                        n("结构用料") = dr(dc.Name)
                    End If
            End Select
        Next
        dr("转换") = True
    Next
    Tables("BOM").ResumeRedraw
End If

此主题相关图片如下：snap1.jpg

If dr.IsNull(dc.Name) = False Then
    Dim n As Row = Tables("BOM").Addnew

改成

If dr.IsNull(dc.Name) = False Then
    Dim n As dataRow = dataTables("BOM").find("产品代码 = \'" & dr("产品代码") & "\' and 材料分类 = \'" & dc.name & "\'")

    if n is nothing then

         n = dataTables("BOM").addnew

    End If

还不会写那就上传具体实例