这个意思？

Select Case e.DataCol.Name
    Case "日期","员工"
        If e.DataRow.IsNull("日期") Then
            e.DataRow("计数") = Nothing
        Else
            Dim max As String \'最大编号
            Dim idx As Integer
            Dim rq As String = e.DataRow("日期")
            Dim yg As String = e.DataRow("员工")
            max = e.DataTable.Compute("Max(计数)","日期 = \'"& rq &"\' And 员工 = \'"& yg &"\' And [_Identify] <> " & e.DataRow("_Identify")) \'取得最大计数
            If max > "" Then \'如果存在最大计数
                idx = CInt(max) + 1 \'获得最大计数,并加1
            Else
                idx = 1 \'否则顺序号等于1
            End If
            e.DataRow("计数") = idx
        End If
    Case "工时"
        For Each dr As DataRow In e.DataTable.Select("[_SortKey] >= " & e.DataRow("_SortKey"))
            Dim Val1 As Double = e.DataTable.Compute("Sum(工时)","[_SortKey] <= " & e.DataRow("_SortKey") & " and 员工 = \'" & e.DataRow("员工") & "\'")
            dr("累计工时") = Val1
        Next
End Select

http://www.foxtable.com/help/topics/1572.htm

http://www.foxtable.com/help/topics/2136.htm

 你要重置列 【工时】

 或者修改了工时列的内容。