主题：请教 逻辑方法

Dim dr As DataRow = e.DataRow
Select Case e.DataCol.Name
    Case "物料系数"
        If  dr.IsNull("物料系数") = False And dr.IsNull("加工级别") = False And dr.IsNull("组件序号") = False   Then
            If dr("加工级别") = 1 Then
                dr("系数统计") = dr("物料系数")
            Else
                Dim ab As Byte = dr("加工级别") - 1
                Dim dr2,dr3,dr4 As DataRow
               
                Dim idx As Integer = dr("组件序号").LastIndexOf(".")
                Dim pstr As String = ""
                If idx > -1 Then pstr = dr("组件序号").SubString(0, idx)
               
                Dim Filter As String = "组件序号 like '" & pstr & "%' and 加工级别 =  '" & ab  & "'    "

                dr2 = DataTables("表A").find(Filter, "组件序号")
               
                If dr2 Is Nothing Then
                    dr("系数统计") = dr("物料系数")
                Else
                    dr("系数统计") = dr("物料系数") * dr2("系数统计")
                End If
            End If
           
        End If
End Select