标题：如何只自动统计最后10行的数据？

统计订单表最后10行：

Dim dt As DataTable = DataTables("订单")
Dim idx As Integer = math.max(0,dt.DataRows.count - 10)
Dim g As New GroupTableBuilder("统计表1", dt)
g.Filter = "[_Identify] >= " & dt.DataRows(idx)("_identify")
g.Groups.AddDef("日期", "月")
g.Totals.AddDef("数量")
g.Build()
MainTable = Tables("统计表1")