private void UpdateOperation()
        {
            int id = -1;

            while (id < 0)
            {
                id = view.EnterId();
            }
            if (id < 0)
            {
                throw new Exception("Wrong id");
            }
            switch (view.entity)
            {
            case Entity.Room:
                Room room = view.RoomAddOrUpdateEnter();
                room.Id = id;
                roomDAO.Update(room);
                break;

            case Entity.Guest:
                Guest guest = view.GuestAddOrUpdateEnter();
                guest.Id = id;
                guestDAO.Update(guest);
                break;

            case Entity.Booking:
                Booking booking = view.BookingAddOrUpdate();
                booking.Id = id;
                bookingDAO.Update(booking);
                break;
            }
            view.Success();
        }