Hibernate——QBC（七）

分页、排序查询操作

Session currentSession = HibernateUtil.getCurrentSession();
Transaction transaction = currentSession.beginTransaction();
Criteria criteria = currentSession.createCriteria(User.class);
criteria.addOrder(Order.desc("user_id"));//根据某个条件排序
criteria.setFirstResult(1);//角标和要查询的条数
criteria.setMaxResults(2);
List<User> list = criteria.list();
for (User user : list) {
    System.out.println(user);
}

transaction.commit();
currentSession.close();

 

条件判断查询

Session currentSession = HibernateUtil.getCurrentSession();
Transaction transaction = currentSession.beginTransaction();
Criteria criteria = currentSession.createCriteria(User.class);
criteria.add(Restrictions.eq("user_name","user1"));
criteria.add(Restrictions.like("user_code","u%"));

List<User> list = criteria.list();
for (User user : list) {
    System.out.println(user);
}

transaction.commit();
currentSession.close();

聚合函数的使用

Session currentSession = HibernateUtil.getCurrentSession();
Transaction transaction = currentSession.beginTransaction();
Criteria criteria = currentSession.createCriteria(User.class);
//setProjection 设置聚合函数
criteria.setProjection(Projections.rowCount());
Object o = criteria.uniqueResult();
System.out.println(o);

transaction.commit();
currentSession.close();

离线查询

作用附上大佬链接：https://blog.csdn.net/github_36116217/article/details/52599464

DetachedCriteria detachedCriteria = DetachedCriteria.forClass(User.class);
detachedCriteria.add(Restrictions.eq("user_name","user1"));
Session currentSession = HibernateUtil.getCurrentSession();
Transaction transaction = currentSession.beginTransaction();
//绑定session
Criteria executableCriteria = detachedCriteria.getExecutableCriteria(currentSession);
List<User> list = executableCriteria.list();
for (User user : list) {
    System.out.println(user);
}
transaction.commit();
currentSession.close();