private void DeleteOperation() { int id = -1; while (id < 0) { id = view.EnterId(); } if (id < 0) { throw new Exception("Wrong id"); } switch (view.entity) { case Entity.Room: roomDAO.Delete(id); break; case Entity.Guest: guestDAO.Delete(id); break; case Entity.Booking: bookingDAO.Delete(id); break; } view.Success(); }