使用where子句在hibernate中选择查询

Question

I have class Login which has userId , username and password .

For a user to login I am checking username and password and geting userId . If userId is not zero then it will lead to home page. I am trying to do this in hibernate. But my query is not working

public int userLogin(Login login)
        throws MySQLIntegrityConstraintViolationException, SQLException,
        Exception {

    Session session = HibernateUtil.getSessionFactory().openSession();
    int userId = 0;

    try {
            session.beginTransaction();
            String hql = "Select log.userId from Login log where log.userName=:userName 
            and log.password=:password";      
            System.out.println(hql);
            Query query = session.createQuery(hql);
            query.setParameter(":userName", login.getUserName());
            query.setParameter(":password", login.getPassword());
            List result = query.list();

            System.out.println("resultset:"+result);

            Iterator iterator = result.iterator();
            while(iterator.hasNext()){
                userId = (int) iterator.next();


        }
    } catch (HibernateException e) {
        if (session.getTransaction() != null) {
            session.getTransaction().rollback();
        }
    } finally {
        session.close();
    }

Answer 1

1) You are using HQL, so you need to understand that you can't give column names which are in database in projections of HQL query

 String hql = "select user_id from login where user_name= :username and  
            password= :password";

Here in your Login class you don't have field as user_id and you gave user_id into projections. HQL maps class with database, hence Login class will login table and userId field will be user_id column in database.And what you wrote is plain SQL query not HQL query.

Please use this HQL query.

String hql="Select log.userId from Login log where log.username=:username and log.password=:password"

Here log is alias name like we do in plain Java.

Login log=new Login()
log.userId

Answer 2

设置参数时尽量不要使用冒号。

query.setParameter("userName", login.getUserName());