Add aggregate rows to a table

    Protected Function AggregatedTable(ByVal TableToAggregate As Data.DataTable, ByVal SortFieldName As String, ByVal FieldsToAggregate() As String) As Data.DataTable
        Dim ReturnTable As Data.DataTable = New Data.DataView(TableToAggregate, Nothing, SortFieldName, Data.DataViewRowState.CurrentRows).ToTable
        Dim RowNumberColumn As New Data.DataColumn
        RowNumberColumn.ColumnName = "Row~Number"
        RowNumberColumn.DataType = GetType(Integer)
        ReturnTable.Columns.Add(RowNumberColumn)
        Dim RowsToAddList As New Generic.List(Of Data.DataRow)
        Do
            Dim NewRow As Data.DataRow = ReturnTable.NewRow
            ReturnTable.Rows.Add(NewRow)
            Exit Do
        Loop
        Dim LastMatch As String = "~"
        Dim LastRowNumber As New Integer
        For Each ReturnRow As Data.DataRow In ReturnTable.Rows
            ReturnRow.Item("Row~Number") = ReturnTable.Rows.IndexOf(ReturnRow) * 2
            LastRowNumber = ReturnRow.Item("Row~Number")
            If LastMatch <> "~" Then
                If LastMatch <> ReturnRow.Item(SortFieldName).ToString Then
                    Dim NewRow As Data.DataRow = ReturnTable.NewRow
                    NewRow.Item("Row~Number") = ReturnRow.Item("Row~Number") - 1
                    NewRow.Item("RowFont") = "Bold"
                    If ReturnTable.Compute("Sum(Grand_Inv_Total)", String.Format("(Exported = 'True') AND (Salesman1 = '{0}')", Server.HtmlEncode(LastMatch))) IsNot DBNull.Value Then
                        Dim Exported As Decimal = ReturnTable.Compute("Sum(Grand_Inv_Total)", String.Format("(Exported = 'True') AND (Salesman1 = '{0}')", LastMatch))
                        Dim ExportedPercent As Decimal = Exported / ReturnTable.Compute("Sum(Grand_Inv_Total)", String.Format("(Salesman1 = '{0}')", LastMatch))
                        NewRow.Item("Cust_Name") = "Exported: " & Exported.ToString("c") & StrDup(3, ChrW(160)) & ExportedPercent.ToString("p")
                    End If
                    NewRow.Item(SortFieldName) = LastMatch
                    For Each AggregateField In FieldsToAggregate
                        Dim FormatString As String = String.Format("Sum({0})", AggregateField)
                        Dim FilterString As String = String.Format("{0} = '{1}'", SortFieldName, LastMatch.Replace("'", "''"))
                        NewRow.Item(AggregateField) = ReturnTable.Compute(FormatString, FilterString)
                    Next AggregateField
                    RowsToAddList.Add(NewRow)
                End If
            End If
            LastMatch = ReturnRow.Item(SortFieldName).ToString
        Next ReturnRow
        For Each RowToAdd As Data.DataRow In RowsToAddList
            ReturnTable.Rows.Add(RowToAdd)
        Next RowToAdd
        ReturnTable = New Data.DataView(ReturnTable, "[Row~Number] <> " & LastRowNumber, "Row~Number", Data.DataViewRowState.CurrentRows).ToTable
        ReturnTable.Columns.Remove("Row~Number")
        Return ReturnTable
    End Function