07-Hibernate查询HQL，Criteria，原生SQL查询总结及语法详解

07-Hibernate查询HQL，Criteria，原生SQL查询总结及语法详解

• 查询HQL，Criteria，原生SQL查询总结及语法详解

  • 查询HQL语法

    • OID查询—get

    • 对象属性导航查询

    • HQL

    • 单表查询语法练习

      //基本语法
      	@Test
      	public void fun1(){
      		Session session = HibernateUtils.openSession();
      		Transaction tx = session.beginTransaction();
      		//-----------------------------------------
      		String hql = "from com.qingzi.domain.Customer";
      		String hql1 = "from Customer";
      		String hql2 = "from java.lang.Object";
      		
      		Query query = session.createQuery(hql2);
      		List list = query.list();
      		System.out.println(list);
      		
      		//-----------------------------------------
      		tx.commit();
      		session.close();
      	}
      

      //排序
      	@Test
      	public void fun2(){
      		Session session = HibernateUtils.openSession();
      		Transaction tx = session.beginTransaction();
      		//-----------------------------------------
      		String hql = "from com.qingzi.domain.Customer order by cust_id asc";
      		String hql1 = "from com.qingzi.domain.Customer order by cust_id desc";
      		Query query = session.createQuery(hql1);
      		List list = query.list();
      		System.out.println(list);
      		//-----------------------------------------
      		tx.commit();
      		session.close();
      	}
      

      //条件查询
      	@Test
      	public void fun3(){
      		Session session = HibernateUtils.openSession();
      		Transaction tx = session.beginTransaction();
      		//-----------------------------------------
      		String hql = "from com.qingzi.domain.Customer where cust_id = ?";
      		String hql1 = "from com.qingzi.domain.Customer where cust_id = :cust_id";
      		Query query = session.createQuery(hql1);
      		
      		//query.setParameter(0, 1l);
      		query.setParameter("cust_id", 1l);
      		List list = query.list();
      		System.out.println(list);
      		//-----------------------------------------
      		tx.commit();
      		session.close();
      	}
      

      	//分页查询
      	@Test
      	public void fun4(){
      		Session session = HibernateUtils.openSession();
      		Transaction tx = session.beginTransaction();
      		//-----------------------------------------
      		String hql = "from com.qingzi.domain.Customer";
      		Query query = session.createQuery(hql);
      		
      		//(当前页码-1)*每页条数
      		query.setFirstResult(1);
      		query.setMaxResults(2);
      		
      		List list = query.list();
      		System.out.println(list);
      		//-----------------------------------------
      		tx.commit();
      		session.close();
      	}
      

      // 统计查询
      	//count 计数
      	//sum  求和
      	//avg  平均数
      	//max 求最大值
      	//min 求最小值
      	@Test
      	public void fun5(){
      		Session session = HibernateUtils.openSession();
      		Transaction tx = session.beginTransaction();
      		//-----------------------------------------
      		String hql1 = "select count(*) from com.qingzi.domain.Customer ";//完整写法
      		String hql2 = "select sum(cust_id) from com.qingzi.domain.Customer ";//完整写法
      		String hql3 = "select avg(cust_id) from com.qingzi.domain.Customer ";//完整写法
      		String hql4 = "select max(cust_id) from com.qingzi.domain.Customer ";//完整写法
      		String hql5 = "select min(cust_id) from com.qingzi.domain.Customer ";//完整写法
      		Query query = session.createQuery(hql5);
      		Number number = (Number) query.uniqueResult();
      		System.out.println(number);
      		//-----------------------------------------
      		tx.commit();
      		session.close();
      	}
      

      //投影查询
      	@Test
      	public void fun6(){
      		Session session = HibernateUtils.openSession();
      		Transaction tx = session.beginTransaction();
      		//-----------------------------------------
      		String hql1 = "select cust_name from com.qingzi.domain.Customer ";
      		String hql2 = "select cust_name,cust_id from com.qingzi.domain.Customer ";
      		String hql3 = "select new Customer(cust_id,cust_name) from com.qingzi.domain.Customer ";
      		Query query = session.createQuery(hql3);
      		
      		List list = query.list();
      		System.out.println(list);
      		//-----------------------------------------
      		tx.commit();
      		session.close();
      	}
      

    • 多表查询语法练习（不常用）

      • 内连接(迫切)
      • 外链接
        • 左外（迫切）
        • 右外（迫切）

      //基本语法
      	@Test
      	public void fun1(){
      		//HQL 内连接=》将连接的两端对象分别返回，放到数据库中。
      		Session session = HibernateUtils.openSession();
      		Transaction tx = session.beginTransaction();
      		//---------------------------------------------------------
      		String hql = "from Customer c inner join c.linkMens ";
      		
      		Query query = session.createQuery(hql);
      			List<Object[]> list = query.list();
      			for(Object[]arr :list){
      				System.out.println(Arrays.toString(arr));
      				
      			}
      		
      		
      		//----------------------------------------------------------
      		tx.commit();
      		session.close();
      	}
      

      //基本语法
      		@Test
      		public void fun2(){
      			
      			//HQL 迫切内连接 =》帮我们封装，返回值就是一个对象
      			Session session = HibernateUtils.openSession();
      			Transaction tx = session.beginTransaction();
      			//---------------------------------------------------------
      			String hql = "from Customer c inner join fetch c.linkMens ";
      			
      			Query query = session.createQuery(hql);
      			List<Customer> list = query.list();
      				
      			System.out.println(list);
      			
      			//----------------------------------------------------------
      			tx.commit();
      			session.close();
      	}
      

      //基本语法
      	@Test
      	public void fun3(){
      		
      		//HQL  左外连接=》将连接的两端对象分别返回，放到数据库中。
      		Session session = HibernateUtils.openSession();
      		Transaction tx = session.beginTransaction();
      		//---------------------------------------------------------
      		String hql = "from Customer c left join c.linkMens ";
      		
      		Query query = session.createQuery(hql);
      			List<Object[]> list = query.list();
      			for(Object[]arr :list){
      				System.out.println(Arrays.toString(arr));
      				
      			}
      		
      		
      		//----------------------------------------------------------
      		tx.commit();
      		session.close();
      	}
      

      //基本语法
      	@Test
      	public void fun4(){
      		
      		//HQL  右外连接=》将连接的两端对象分别返回，放到数据库中。
      		Session session = HibernateUtils.openSession();
      		Transaction tx = session.beginTransaction();
      		//---------------------------------------------------------
      		String hql = "from Customer c right join c.linkMens ";
      		
      		Query query = session.createQuery(hql);
      			List<Object[]> list = query.list();
      			for(Object[]arr :list){
      				System.out.println(Arrays.toString(arr));
      				
      			}
      		
      		
      		//----------------------------------------------------------
      		tx.commit();
      		session.close();
      	}
      

  • 学习Criteria语法详解

    //学习criteria
    public class Demo {
    	
    	//基本语法
    	@Test
    	public void fun1(){
    		Session session = HibernateUtils.openSession();
    		Transaction tx = session.beginTransaction();
    		//---------------------------------------------------------
    		
    		Criteria c = session.createCriteria(Customer.class);
    		
    		List<Customer> list = c.list();
    		System.out.println(list);
    		//----------------------------------------------------------
    		tx.commit();
    		session.close();
    	}
    		
    	//条件查询
    	@Test
    	public void fun2(){
    		Session session = HibernateUtils.openSession();
    		Transaction tx = session.beginTransaction();
    		//---------------------------------------------------------
    		Criteria criteria = session.createCriteria(Customer.class);
    		criteria.add(Restrictions.idEq(1l));
    		criteria.add(Restrictions.eq("cust_id", 1l));
    		
    		List<Customer> list = criteria.list();
    		System.out.println(list);
    		//----------------------------------------------------------
    		tx.commit();
    		session.close();
    	}
    	
    	//分页语法  与HQL一样
    	@Test
    	public void fun3(){
    		Session session = HibernateUtils.openSession();
    		Transaction tx = session.beginTransaction();
    		//---------------------------------------------------------
    		Criteria c = session.createCriteria(Customer.class);
    		//limit ？，？
    		c.setFirstResult(1);
    		c.setMaxResults(2);
    		
    		List<Customer> list = c.list();
    		System.out.println(list);
    		//----------------------------------------------------------
    		tx.commit();
    		session.close();
    	}
    	
    	//排序语法
    	@Test
    	public void fun4(){
    		Session session = HibernateUtils.openSession();
    		Transaction tx = session.beginTransaction();
    		//---------------------------------------------------------
    		Criteria c = session.createCriteria(Customer.class);
    		c.addOrder(Order.asc("cust_id"));
    		c.addOrder(Order.desc("cust_id"));
    		
    		List<Customer> list = c.list();
    		System.out.println(list);
    		//----------------------------------------------------------
    		tx.commit();
    		session.close();
    	}
    	
    	//统计语法
    	@Test
    	public void fun5(){
    		Session session = HibernateUtils.openSession();
    		Transaction tx = session.beginTransaction();
    		//---------------------------------------------------------
    		Criteria c = session.createCriteria(Customer.class);
    		
    		//设置查询目标
    		c.setProjection(Projections.rowCount());
    		
    		List<Customer> list = c.list();
    		System.out.println(list);
    		//----------------------------------------------------------
    		tx.commit();
    		session.close();
    	}
    }
    

  • 学习离线Criteria

    public class Demo2 {
    	@Test
    	public void fun1(){
    		//Service/web
    		DetachedCriteria dc = DetachedCriteria.forClass(Customer.class);
    		
    		dc.add(Restrictions.idEq(1l));//瓶装条件(全部与普通Criteria一致)
    		
    		//--------------------------------------------------
    		Session session = HibernateUtils.openSession();
    		Transaction tx = session.beginTransaction();
    		
    		//------------------------------------------------
    		Criteria c = dc.getExecutableCriteria(session);
    		List list = c.list();
    		
    		System.out.println(list);
    		
    		tx.commit();
    		session.close();
    	}
    }