Components for Delphi and C++ Builder.

procedure TForm1.DBGridEh1SelectionChanged(Sender: TObject);
begin
  if (DBGridEh1.SelectedRows.Count = 0) then
  begin
    DBGridEh1.FieldColumns['Area'].Footer.ValueType := fvtSum;
  end else
  begin
    DBGridEh1.FieldColumns['Area'].Footer.ValueType := fvtStaticText;
    DBGridEh1.FieldColumns['Area'].Footer.Value := CalcSelectedRows.ToString;
  end;
end;

function TForm1.CalcSelectedRows: Double;
var
  I: Integer;
  MemRec: TMemoryRecordEh;
begin
  Result := 0;
  for I := 0 to DBGridEh1.SelectedRows.Count - 1 do
  begin
    MemRec := MemTableEh1.BookmarkToRec(DBGridEh1.SelectedRows[i]);
    MemTableEh1.InstantReadEnter(MemRec, -1);
    Result := Result + MemTableEh1.FieldByName('Area').AsFloat;
    MemTableEh1.InstantReadLeave;
  end;
end;

procedure TForm67.Button1Click(Sender: TObject);
var
  Mem: TMemTableEh;
  Dat: TDataSetDriverEh;
  MemRec: TMemoryRecordEh;
  I:Integer;
begin
  Mem := TMemTableEh.Create(Self);
  Dat := TDataSetDriverEh.Create(Self);
  try
    Dat.ProviderDataSet := DBGridEh1.DataSource.DataSet;
    Mem.DataDriver := Dat;
    Mem.Close;
    Mem.Open;
    for I := 0 to DBGridEh1.SelectedRows.Count - 1 do
    begin
      MemRec := Mem.BookmarkToRec(DBGridEh1.SelectedRows[I]);
      Mem.InstantReadEnter(MemRec, -1);
      ShowMEssage(Mem.FieldByName('ESTABELEC').AsString);
      Mem.InstantReadLeave;
    end;
  finally
    FreeAndNil(Mem);
    FreeAndNil(Dat);
  end;
end;

    for I := 0 to DBGridEh1.SelectedRows.Count - 1 do
    begin
//      MemRec := Mem.BookmarkToRec(DBGridEh1.SelectedRows[I]);
//      Mem.InstantReadEnter(MemRec, -1);
//      ShowMEssage(Mem.FieldByName('ESTABELEC').AsString);
//      Mem.InstantReadLeave;
        cds.GotoBookmark(DBGridEh1.SelectedRows[I]);
        ShowMEssage(cds.FieldByName('ESTABELEC').AsString);
    end;