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();
