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Hibernate之Query接口的uniqueResult()方法

分類： Hibernate 2011-12-26 21:15  6769人閱讀  評論(1)  收藏  舉報

query hibernate session list null

若是查詢返回多個值用list()方法

 

public void testQuery(){
        Configuration config = new Configuration().configure();
        SessionFactory factory = config.buildSessionFactory(); //建立SessionFactory
        Session session = factory.openSession();        //建立Session
        session.beginTransaction();                     //開始事務

        Query query = session.createQuery("from Student");
        List list = query.list();  // 用list方法返回多個值
        //List list = session.createQuery("from Student").list();
        for(int i=0;i<list.size();i++){
            Student student = (Student)list.get(i);
            System.out.print(student.getId()+" ");
            System.out.print(student.getName()+" ");
            System.out.print(student.getSex()+" ");
            System.out.print(student.getBirthday());
            System.out.println();
        }

        session.getTransaction().commit();         //提交事務
        session.close();                           //關閉Session
    }

當肯定返回的實例只有一個或者null時 用uniqueResult()方法

 

 

 

public void testGet(){
        Configuration config = new Configuration().configure();
        SessionFactory factory = config.buildSessionFactory();
        Session session = factory.openSession();
        session.beginTransaction();

        Query query = session.createQuery("from Student s where s.id=?");
        query.setString(0, "2");
        Student student = (Student)query.uniqueResult();  //當肯定返回的實例只有一個或者null時 用uniqueResult()方法
        //Student student = (Student)session.createQuery("from Student s where s.id=?").setString(0,"5").uniqueResult();

        System.out.println(student.getName());
        System.out.println(student.getBirthday());


        session.getTransaction().commit();
        session.close();
    }