private boolean checkInvitation(int eventId, String fromUsername,
			String toUsername) {
		Map<String, Object> parameters = new HashMap<String, Object>();
		parameters.put("eventId", eventId);
		parameters.put("fromUsername", fromUsername);
		parameters.put("toUsername", toUsername);
		int res = -1;
		try {
		res = jdbcTemplate.queryForInt(GET_INVITATION_ID, parameters);
		} catch (EmptyResultDataAccessException e) {
			return false;
		}
		if(res != -1)
			return true;
		return false;
	}