For i As Integer = Tables("表A").count-1 To 0 Step -1
Dim r As Row = Tables("表A").Rows(i)
If i = Tables("表A").count-1
r("累计成本") = r("系数") * r("单价")
Else
If r("加工级别") <> Tables("表A").Rows(i+1)("加工级别")
r("累计成本") = DataTables("表A").Compute("Sum(累计成本)", "加工级别 =" & _
Tables("表A").Rows(i+1)("加工级别") & " ") + r("单价")
Else
r("累计成本") = r("系数") * r("单价")
End If
End If
Next