Hibernate HQL的使用

Posted 2020-10-03 wzzkaifa

1、简单查询（查询所有）

Session session=HibernateUtil.getSessionFactory().getCurrentSession();
Transaction tx=session.beginTransaction();
List<People> peoples=session.createQuery("from People").list();
for(People people:peoples){
	System.out.println(people.getName());
}
tx.commit();

2、依照參数查询

Session session=HibernateUtil.getSessionFactory().getCurrentSession();
Transaction tx=session.beginTransaction();
//1、依照位置进行參数绑定
/*Query query=session.createQuery("from People Where name=?");
  query.setString(0,"小明1");
*/
//2、依照參数名进行參数绑定
Query query=session.createQuery("from People Where name=:name");
query.setString("name","小明1");
List<People> peoples=query.list();
for(People people:peoples){
	System.out.println(people.getName());
}
tx.commit();

3、分页查询

Session session=HibernateUtil.getSessionFactory().getCurrentSession();
Transaction tx=session.beginTransaction();
Query query=session.createQuery("from People");
query.setFirstResult(0);//设置查询開始的起始位置
query.setMaxResults(2);//设置查询的数目
List<People> peoples=query.list();
for(People people:peoples){
	System.out.println(people.getName());
}
tx.commit();

4、聚集函数的使用

Session session=HibernateUtil.getSessionFactory().getCurrentSession();
Transaction tx=session.beginTransaction();
//count()
Query query=session.createQuery("select count(*) from People");
long count=(long) query.uniqueResult();
System.out.println(count);
tx.commit();
//min() max() avg() sum()的使用与count相似

5、in的使用

Session session=HibernateUtil.getSessionFactory().getCurrentSession();
Transaction tx=session.beginTransaction();
String names[]={"小明1","小明2","小明3"};
Query query=session.createQuery("from People where name in (:name)");
query.setParameterList("name",names);
List<People> peoples=query.list();
for(People people:peoples){
	System.out.println(people.getId());
}
tx.commit();