function TFrmMain.GetSum(Gird1:TWDBGrid;FieldName:String;NeedDJ02:boolean):Double;
var
  bm:Tbookmark;
  i:Integer;
  Sum:Double;
begin
  Result := 0;
  If Gird1.DataSource.DataSet.IsEmpty Then Exit;
  Bm := Gird1.DataSource.DataSet.GetBookmark;
  Sum := 0;
  if Gird1.SelectedRows.Count = 0 Then Gird1.SelectedRows.CurrentRowSelected := True;
  for i := 0 To Gird1.SelectedRows.Count -1 Do
  Begin
    Gird1.DataSource.DataSet.GotoBookmark(TBookmark(Gird1.SelectedRows[i]));
    if NeedDJ02 then begin
       if Gird1.DataSource.DataSet.fieldbyName(‘DJ02′).AsString=’國內購買’ then
        Sum := Sum +
           Gird1.DataSource.DataSet.fieldbyName(FieldName).AsFloat
       else
        Sum := Sum -
           Gird1.DataSource.DataSet.fieldbyName(FieldName).AsFloat;
    end else
        Sum := Sum +
           Gird1.DataSource.DataSet.fieldbyName(FieldName).AsFloat;
  End;
  Result := Sum;
End;

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