Hibernate4.3 HQL查询

HQL：Hibernate专属语言，可以跨数据库

一、基本查询

 1 public void testQuery(){

 2         Session session = HibernateUtils.getSession();

 3         String hql = "from Person";

 4         Query query = session.createQuery(hql);

 5         List<Person> list = query.list();

 6         for(Person p : list){

 7             System.out.println(p);

 8         }

 9         HibernateUtils.close(session);

10     }

　　单个属性列查询

1 //查询单个属性

2         String hql = "select p.pname from Person p";

3         Query query = session.createQuery(hql);

4         List<String> list = query.list();

　　多个属性查询

1 //查询多列

2         String hql = "select p.id,p.pname from Person p";

3         Query query = session.createQuery(hql);

4         List<Object[]> objArrList = query.list();

5         for(Object[] objArr : objArrList){

6             System.out.println("编号："+objArr[0]+"   姓名："+objArr[1]);

7         }

二、Hibernate分页查询

1 Session session = HibernateUtils.getSession();

2         String hql = "from Person";

3         Query query = session.createQuery(hql);

4         //设置分页查询

5         query.setFirstResult(0);

6         query.setMaxResults(5);

7         List<Person> list = query.list();

三、限定查询

String hql = "from Person  where id = ?";

        Query query = session.createQuery(hql);

        query.setParameter(0, 5);

        List<Person> list = query.list();

1 Session session = HibernateUtils.getSession();

2         String hql = "from Person  where id = :id";

3         Query query = session.createQuery(hql);

4         query.setParameter("id", 5);

5         List<Person> list = query.list();

四、统计查询

1 String hql = "select count(*) from Person p";

2         Query query = session.createQuery(hql);

3         Object result =  query.uniqueResult();

五、分组统计查询

1 String hql = "select avg(p.salary),p.pgender from Person p group by p.pgender";

2         Query query = session.createQuery(hql);

3         List<Object[]> objArrList = query.list();

六、投影查询

建立一个业务Bean,在bean提供有参的构造器来接收sql的返回值，创建出对象

七、排序查询

1 String hql = "from Person p order by p.salary desc";

2         Query query = session.createQuery(hql);

3         List<Person> list = query.list();

八、从配置文件中设置查询，然后提取

在 Person.hbm.xml配置文件中
1 <query name="getPerson">

2         <![CDATA[

3             from Person p where p.salary > 400

4         ]]>

5     </query>

1 Query query = session.getNamedQuery("getPerson");

2         List<Person> list = query.list();

巴特西

Hibernate4.3 HQL查询

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