protected virtual void SetSortBySummary()

        {

            foreach (PivotGridField field in grid.Fields)

            {

                if (field.Area == DevExpress.XtraPivotGrid.PivotArea.DataArea)

                {

                    field.CellStyle.Font.Bold = false;

                    field.HeaderStyle.Font.Bold = false;

                }

            }

            PivotGridField selectedField = grid.Fields[ddlSortByField.SelectedItem.Text];

            if (selectedField == null) return;

            selectedField.CellStyle.Font.Bold = true;

            selectedField.HeaderStyle.Font.Bold = true;

            //改变row的field之后改变sort的值

            try

            {

                sort = grid.GetFieldsByArea(DevExpress.XtraPivotGrid.PivotArea.RowArea)[0].ToString();

            }

            catch { }

            grid.Fields[sort].SortBySummaryInfo.FieldName = selectedField.FieldName;

            grid.Fields[sort].SortBySummaryInfo.SummaryType = selectedField.SummaryType;

        }