主题：为什么重置二次才出现正确结果

'下面的代码为什么重置二次才出现正确结果

Select Case e.DataCol.Name
    Case "应分面积"
    Dim drr As  DataRow = e.DataRow
    drr("垂长累计") =( Math.Sqrt(2 * drr("累计面积") * drr("南北垂长") * (drr("北长_下底") - drr("南长_上底")) + drr("南长_上底") * drr("南长_上底") * drr("南北垂长") * drr("南北垂长") ) _
 - drr("南长_上底") * drr("南北垂长") ) / (drr("北长_下底") - drr("南长_上底"))
End Select

Select Case e.DataCol.Name
    Case "田块名称","南长_上底","北长_下底","南北垂长","应分面积"
        Dim dr As DataRow
        Dim mr As DataRow = e.DataRow
        Dim drs As List(of DataRow)
        dr = e.DataTable.Find("[_SortKey] < " & mr("_SortKey") & " And [田块名称] = '" & mr("田块名称") & "'", "[_SortKey] Desc")
        If dr Is Nothing Then
            mr("累计面积") = mr("应分面积")
            mr("户分垂长") = mr("垂长累计")
            mr("实分面积") = mr("验证面积")
            mr("户分东长") = mr("东长累计")
            mr("户分西长") = mr("西长累计")
            dr = mr
        End If
        drs = e.DataTable.Select("[_SortKey] >= " & dr("_SortKey") & " And [田块名称] = '" & dr("田块名称") & "'", "[_SortKey]")
        For i As Integer = 1 To drs.Count - 1
            drs(i)("累计面积") = drs(i-1)("累计面积") + drs(i)("应分面积")
            drs(i)("户分垂长") = drs(i)("垂长累计") - drs(i-1)("垂长累计")
            drs(i)("实分面积") = drs(i)("验证面积") - drs(i-1)("验证面积")
            drs(i)("户分东长") = drs(i)("东长累计") - drs(i-1)("东长累计")
            drs(i)("户分西长") = drs(i)("西长累计") - drs(i-1)("西长累计")
        Next
        If e.DataCol.Name = "田块名称" AndAlso e.OldValue IsNot Nothing AndAlso e.OldValue <> e.NewValue Then
            dr = e.DataTable.Find("[_SortKey] < " & mr("_SortKey") & " And [田块名称] = '" & e.OldValue & "'", "[_SortKey] Desc")
            If dr Is Nothing Then
                dr = e.DataTable.Find("[田块名称] = '" & e.OldValue & "'", "[_SortKey]")
                If dr IsNot Nothing Then
                    dr("累计面积") = dr("应分面积")
                    dr("户分垂长") = dr("垂长累计")
                    dr("实分面积") = dr("验证面积")
                    dr("户分东长") = dr("东长累计")
                    dr("户分西长") = dr("西长累计")
                End If
            End If
            If dr IsNot Nothing Then
                drs = e.DataTable.Select("[_SortKey] >= " & dr("_SortKey") & " And [田块名称] = '" & dr("田块名称") & "'", "[_SortKey]")
                For i As Integer = 1 To drs.Count - 1
                    drs(i)("累计面积") = drs(i-1)("累计面积") + drs(i)("应分面积")  
                    drs(i)("户分垂长") = drs(i)("垂长累计") - drs(i-1)("垂长累计")
                    drs(i)("实分面积") = drs(i)("验证面积") - drs(i-1)("验证面积")
                    drs(i)("户分东长") = drs(i)("东长累计") - drs(i-1)("东长累计")
                    drs(i)("户分西长") = drs(i)("西长累计") - drs(i-1)("西长累计")
                Next
            End If
        End If
End Select

这个需要你做个实例发上来，大家才可以帮你测试和发现问题。
数据就模拟一些会出现这样问题的数据就可以了。

能不能上个例子? 另外你是点击第一次重置没有计算?还是计算错误?  

没有例子？ 也不做任何解释？

什么列输入数据？ 在什么列得出计算结果？ 第一次得出的错误结果是什么？ 第二次重置后得出的正确的结果是社么？

'这样写后正确了，是计算顺序错误引起的。谢谢大家的关心！

Select Case e.DataCol.Name
    Case "田块名称","应分面积"
        Dim dr As DataRow
        Dim mr As DataRow = e.DataRow
        Dim drs As List(of DataRow)
        dr = e.DataTable.Find("[_SortKey] < " & mr("_SortKey") & " And [田块名称] = '" & mr("田块名称") & "'", "[_SortKey] Desc")
        If dr Is Nothing Then
            mr("累计面积") = mr("应分面积")
            dr = mr
        End If
        drs = e.DataTable.Select("[_SortKey] >= " & dr("_SortKey") & " And [田块名称] = '" & dr("田块名称") & "'", "[_SortKey]")
        For i As Integer = 1 To drs.Count - 1
            drs(i)("累计面积") = drs(i-1)("累计面积") + drs(i)("应分面积")
        Next
        If e.DataCol.Name = "田块名称" AndAlso e.OldValue IsNot Nothing AndAlso e.OldValue <> e.NewValue Then
            dr = e.DataTable.Find("[_SortKey] < " & mr("_SortKey") & " And [田块名称] = '" & e.OldValue & "'", "[_SortKey] Desc")
            If dr Is Nothing Then
                dr = e.DataTable.Find("[田块名称] = '" & e.OldValue & "'", "[_SortKey]")
                If dr IsNot Nothing Then
                    dr("累计面积") = dr("应分面积")
                End If
            End If
            If dr IsNot Nothing Then
                drs = e.DataTable.Select("[_SortKey] >= " & dr("_SortKey") & " And [田块名称] = '" & dr("田块名称") & "'", "[_SortKey]")
                For i As Integer = 1 To drs.Count - 1
                    drs(i)("累计面积") = drs(i-1)("累计面积") + drs(i)("应分面积")  
                Next
            End If
        End If

'对某列开平方

    Case "南长_上底","北长_下底","南北垂长","累计面积"
       If e.DataRow("南长_上底") = e.DataRow("北长_下底") Then
         e.DataRow("垂长累计")  = e.DataRow("累计面积") / e.DataRow("南长_上底")
       Else
               '对某列开平方
          e.DataRow("垂长累计") =( Math.Sqrt(2 * e.DataRow("累计面积") * e.DataRow("南北垂长") * (e.DataRow("北长_下底") - e.DataRow("南长_上底")) + e.DataRow("南长_上底") * e.DataRow("南长_上底") * e.DataRow("南北垂长") * e.DataRow("南北垂长") ) _
 - e.DataRow("南长_上底") * e.DataRow("南北垂长") ) / (e.DataRow("北长_下底") - e.DataRow("南长_上底"))
      End If

 

    Case "田块名称","东长","西长","垂长累计"
        Dim dr As DataRow
        Dim mr As DataRow = e.DataRow
        Dim drs As List(of DataRow)
        dr = e.DataTable.Find("[_SortKey] < " & mr("_SortKey") & " And [田块名称] = '" & mr("田块名称") & "'", "[_SortKey] Desc")
        If dr Is Nothing Then
            mr("户分垂长") = mr("垂长累计")
            mr("实分面积") = mr("验证面积")
            mr("户分东长") = mr("东长累计")
            mr("户分西长") = mr("西长累计")
            dr = mr
        End If
        drs = e.DataTable.Select("[_SortKey] >= " & dr("_SortKey") & " And [田块名称] = '" & dr("田块名称") & "'", "[_SortKey]")
        For i As Integer = 1 To drs.Count - 1
            drs(i)("户分垂长") = drs(i)("垂长累计") - drs(i-1)("垂长累计")
            drs(i)("实分面积") = drs(i)("验证面积") - drs(i-1)("验证面积")
            drs(i)("户分东长") = drs(i)("东长累计") - drs(i-1)("东长累计")
            drs(i)("户分西长") = drs(i)("西长累计") - drs(i-1)("西长累计")
        Next
        If e.DataCol.Name = "田块名称" AndAlso e.OldValue IsNot Nothing AndAlso e.OldValue <> e.NewValue Then
            dr = e.DataTable.Find("[_SortKey] < " & mr("_SortKey") & " And [田块名称] = '" & e.OldValue & "'", "[_SortKey] Desc")
            If dr Is Nothing Then
                dr = e.DataTable.Find("[田块名称] = '" & e.OldValue & "'", "[_SortKey]")
                If dr IsNot Nothing Then
                    dr("户分垂长") = dr("垂长累计")
                    dr("实分面积") = dr("验证面积")
                    dr("户分东长") = dr("东长累计")
                    dr("户分西长") = dr("西长累计")
                End If
            End If
            If dr IsNot Nothing Then
                drs = e.DataTable.Select("[_SortKey] >= " & dr("_SortKey") & " And [田块名称] = '" & dr("田块名称") & "'", "[_SortKey]")
                For i As Integer = 1 To drs.Count - 1
                    drs(i)("户分垂长") = drs(i)("垂长累计") - drs(i-1)("垂长累计")
                    drs(i)("实分面积") = drs(i)("验证面积") - drs(i-1)("验证面积")
                    drs(i)("户分东长") = drs(i)("东长累计") - drs(i-1)("东长累计")
                    drs(i)("户分西长") = drs(i)("西长累计") - drs(i-1)("西长累计")
                Next
            End If
        End If
End Select