Hibernate之Query接口的uniqueResult()方法

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如果查询返回多个值用list()方法

public void testQuery(){  
        Configuration config = new Configuration().configure();  
        SessionFactory factory = config.buildSessionFactory(); //创建SessionFactory  
        Session session = factory.openSession();        //创建Session  
        session.beginTransaction();                     //开始事务  
          
        Query query = session.createQuery("from Student");  
        List list = query.list();  // 用list方法返回多个值  
        //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();         //提交事务   
        session.close();                           //关闭Session  
    }  

当确定返回的实例只有一个或者null时 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();  //当确定返回的实例只有一个或者null时 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();  
    }