hibernate连接oracle查询语句的有关问题。查询方法连接sql server没有有关问题。可是数据库换成oracle查不到结果

public User checkUser(final User user){        return (User) getHibernateTemplate().execute(new HibernateCallback() {            public Object doInHibernate(Session session) throws HibernateException,                    SQLException {                // TODO Auto-generated method stub                Query query = session.createQuery("from User where username = ? and password = ?");                query.setString(0, user.getUsername());                query.setString(1, user.getPassword());                return query.uniqueResult();            }        });    }