hibernate Criteria查询

Criteria对象提供了一种面向对象的方式查询数据库。
Criteria对象需要使用Session对象来获得一个Criteria对象表示对一个
持久化类的查询

查询所有

    Session session = HibernateUtil.getSession();
        session.beginTransaction();
        Criteria cri = session.createCriteria(User.class);
        List<User> list = cri.list();
        for(User user : list) {
            System.out.println(user.getId() + " : " + user.getUsername());
        }
        session.getTransaction().commit();
        

where

//1 
        Session session = HibernateUtil.getSession();
        session.beginTransaction();
        Criteria cri = session.createCriteria(User.class);
        
        //条件 
        cri.add(Restrictions.eq("username", "u1"));
        
        
        List<User> list = cri.list();
        for(User user : list) {
            System.out.println(user.getId() + " : " + user.getUsername());
        }
                  session.getTransaction().commit();
//2 
        
        Session session = HibernateUtil.getSession();
        session.beginTransaction();
        Criteria cri = session.createCriteria(User.class);
        
        //条件 这是and效果 
        cri.add(Restrictions.eq("username", "u1"));
        cri.add(Restrictions.eq("password","123"));
        
        
        List<User> list = cri.list();
        for(User user : list) {
            System.out.println(user.getId() + " : " + user.getUsername());
        }
          session.getTransaction().commit();
//3 
    
        Session session = HibernateUtil.getSession();
        session.beginTransaction();
        Criteria cri = session.createCriteria(User.class);
        
        //条件 这是or效果
        cri.add(Restrictions.or(Restrictions.eq("username", "u1"),Restrictions.eq("username", "jack")));
        
        
        List<User> list = cri.list();
        for(User user : list) {
            System.out.println(user.getId() + " : " + user.getUsername());
        }
          session.getTransaction().commit();
        
        // like 
        
        Session session = HibernateUtil.getSession();
        session.beginTransaction();
        Criteria cri = session.createCriteria(User.class);
        /*MatchMode.ANYWHERE任何地方 MatchMode.START从开始 MatchMode.END表示u结尾的*/
        cri.add(Restrictions.like("username", "u", MatchMode.ANYWHERE));
        
        
        List<User> list = cri.list();
        for(User user : list) {
            System.out.println(user.getId() + " : " + user.getUsername());
        }    
         session.getTransaction().commit();

分页

cri.setFirstResult(0);
cri.setMaxResults(5);

分组与统计

Creteria cri = session createCriteria(User.class);
    cri.setProjection(Projections.count("id"));
    Long count = (Long)cri.uniqueResult();
    syso(count);

多个统计与分组 

Creteria cri = session createCriteria(User.class);
ProjectionList pList = Projections.projectionList();
pList.add(Projections.max("id"));
pList.add(Projections.min("id"));

cri.setProjection(pList);

Object[] array = (Object[]) cri.uniqueResult();
System.out.println(array[0] + " : " +array[1]);

排序 

Session session = HibernateUtil.getSession();
        session.beginTransaction();
        Criteria cri = session.createCriteria(User.class);
        
        cri.addOrder(Order.desc("id"));
        cri.addOrder(Order.asc("username"));

        
        List<User> list = cri.list();
        for(User user : list) {
            System.out.println(user.getId() + " : " + user.getUsername());
        }
 session.getTransaction().commit();

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当然也可以使用原生sql

Session session = HibernateUtil.getSession();
        session.beginTransaction();
        
        
        
        String sql = "select * from user";
        SQLQuery query = session.createSQLQuery(sql);
        List<Object[]> list = query.list();
        
        for(Object[] array : list) {
            System.out.println(array[0] + " : " + array[1]);
        }    
        
        
        
        
        
        String sql = "select * from user";
        SQLQuery query = session.createSQLQuery(sql).addEntity(User.class);
        List<User> list = query.list();
        
        for(User user : list) {
            System.out.println(user.getId() + " : " + user.getUsername());
        }