應該這樣:
Dim g As New GroupTableBuilder("统计表1", DataTables("表A"))
g.Groups.AddDef("日期", DateGroupEnum.Year, "年")
g.Groups.AddDef("日期", "月")
g.Groups.AddDef("产品名称")
g.Totals.AddDef("数量")
g.Totals.AddDef("数量","截止",True)
g.Build()
Dim drs As List(of DataRow)
drs = DataTables("统计表1").Select("产品名称 > ''")
drs(0)("截止") = drs(0)("数量")
For n1 As Integer = 1 To drs.count-1
If drs(n1)("产品名称") = drs(n1-1)("产品名称") Then
drs(n1)("截止") = drs(n1-1)("截止") + drs(n1)("数量")
Else
drs(n1)("截止") = drs(n1)("数量")
End If
Next
MainTable = Tables("统计表1")