每日一得--hibernate高级查询笔记

hibernate高级查询分三种查询方式：

第一种，标准化对象查询

主要由四部分组成：Criteria、Critertion、Order、Projection

一般查询条件封装示例：

Criteria cri = session.createCriteria(Student.class);

Criterion cron  = Restrictions.like("张三",name); //查询条件

cri.add(cron);

cri.addOrder(Order.asc("age")) //排序

List<Student> list = cri.list();

聚合:

Criteria cri = session.createCriteria(Student.class);

cri.setProjection(Projections.rowCount());  //聚合分组

cri.setProjection(Projections.groupProperty("name"));

List<Long> list = (List<Long>)cri.list();

离线查询：

DetachedCriteria dc = DetachedCriteria.forClass(Student.class)

Criteria cri  = dc.getExecutableCriteria(session);

List<Student> list = cri.list();

第二种，HQL语言查询（fetch一次查询查询出相关联的对象）

相关示例如下：

String sql  = "select * from Student a ";

List<Student> list = session.createQuery(sql  ).list();

String sql2  = "select * from Student a inner join a.score s with s.score = 100 ";

List<Student> list2 = session.createQuery(sql2).list();

fetch和with不能同时使用

第三种，原生Native sql查询：

一般查询相关示例如下：

String sql  = "select * from t_bd_student s";

SQLQuery query = session.createSQLQuery(sql).addEntity(Student.class);

List<Student> list = query.list();

关联查询示例：

String sql  = "select {a.*},{s.*} from t_bd_student s join t_bd_score c on s.studentId= c.studentId";

SQLQuery query = session.createSQLQuery(sql).addEntity("a",Student.class).addEntity("b",Score.class);

List  list = query.list();

for(int i = 0 ;i<list.size();i++){

Object[] obj = (Object[])list.get(i);

Student s = (Student)obj[0];

        Score c  = (Score)obj[1];

}

hibernate调用存储过程

SQLQuery query = session.createSQLQuery("{call findStudents(:id)}").addEntity(Student.class);

query.setInteger("id",1);

List<Student> list  = query.list();