主题：流水账计算结果不让显示0或负数

e.datarow("abc") = xxx 赋值的时候，先对xxx进行判断，如果是 <= 0 的数据，就设置成nothing

If xxx <= 0 Then

    e.datarow("abc") = nothing

else

    e.datarow("abc") = xxx

End If

参考

http://www.foxtable.com/webhelp/scr/1572.htm

http://www.foxtable.com/webhelp/scr/2136.htm

比如代码

Select Case e.DataCol.Name
    Case "收入","支出"
        For Each dr As DataRow In e.DataTable.Select("[_SortKey] >= " & e.DataRow("_SortKey"))
            Dim Val1 As Double = e.DataTable.Compute("Sum(收入)","[_SortKey] <= " & dr("_SortKey"))
            Dim Val2 As Double = e.DataTable.Compute("Sum(支出)","[_SortKey] <= " & dr("_SortKey"))
            Dim v = Val1 - Val2
            If v <= 0 Then
                dr("余额") = Nothing
            Else
                dr("余额") = v
            End If
        Next
End Select