public void addToCar(int idCar, String participantName){
		tx.begin();
		Car car = manager.find(Car.class, idCar);
		try {
			Participant participant = (Participant) manager.createQuery(
					"SELECT p FROM Participant p WHERE p.name='"+participantName+"'").getSingleResult();
			participant.setCar(car);
			car.getPassengers().add(participant);
			car.takeSeat();
		} catch ( NoResultException e ) {
			System.err.println("Unable to find participant called "+participantName);
		}
		tx.commit();
	}