主题：统计

Dim dt As DataTable = DataTables("统计")

Dim arys As List(of String()) = dt.GetUniqueValues("", "学科", "层次")

For Each ary() As String In arys

    Dim drs As List(of DataRow) = dt.Select("学科 = '" & ary(0) & "' and 层次 = '" & ary(1) & "'", "班级教学平均分 desc")

    drs(0)("平均分排名") = 1

    For i As Integer = 1 To drs.Count - 1

        If drs(i)("班级教学平均分") = drs(i-1)("班级教学平均分") Then

            drs(i)("平均分排名") = drs(i-1)("平均分排名")

        Else

            drs(i)("平均分排名") = i+1

        End If

    Next

Next