hibernate Criteria查询 2.3

[b]Criteria对象提供了一种面向对象的方式查询数据库。[/b]
[b]Criteria对象需要使用Session对象来获得一个Criteria对象表示对一个[/b]
[b]持久化类的查询[/b]

[b]查询所有[/b]

Session session = HibernateUtil.getSession();
session.beginTransaction();
Criteria cri = session.createCriteria(User.class);
List<User> list = cri.list();
for(User user : list) {
System.out.println(user.getId() + " : " + user.getUsername());
}
session.getTransaction().commit();

where

//1
Session session = HibernateUtil.getSession();
session.beginTransaction();
Criteria cri = session.createCriteria(User.class);

//条件
cri.add(Restrictions.eq("username", "u1"));

List<User> list = cri.list();
for(User user : list) {
System.out.println(user.getId() + " : " + user.getUsername());
}
session.getTransaction().commit();
//2

Session session = HibernateUtil.getSession();
session.beginTransaction();
Criteria cri = session.createCriteria(User.class);

//条件 这是and效果
cri.add(Restrictions.eq("username", "u1"));
cri.add(Restrictions.eq("password","123"));

List<User> list = cri.list();
for(User user : list) {
System.out.println(user.getId() + " : " + user.getUsername());
}
session.getTransaction().commit();
//3

Session session = HibernateUtil.getSession();
session.beginTransaction();
Criteria cri = session.createCriteria(User.class);

//条件 这是or效果
cri.add(Restrictions.or(Restrictions.eq("username", "u1"),Restrictions.eq("username", "jack")));

List<User> list = cri.list();
for(User user : list) {
System.out.println(user.getId() + " : " + user.getUsername());
}
session.getTransaction().commit();

// like

Session session = HibernateUtil.getSession();
session.beginTransaction();
Criteria cri = session.createCriteria(User.class);
/*MatchMode.ANYWHERE任何地方 MatchMode.START从开始 MatchMode.END表示u结尾的*/
cri.add(Restrictions.like("username", "u", MatchMode.ANYWHERE));

List<User> list = cri.list();
for(User user : list) {
System.out.println(user.getId() + " : " + user.getUsername());
}
session.getTransaction().commit();

[b]分页[/b]

cri.setFirstResult(0);
cri.setMaxResults(5);

[b]分组与统计[/b]

Creteria cri = session createCriteria(User.class);
cri.setProjection(Projections.count("id"));
Long count = (Long)cri.uniqueResult();
syso(count);

[b]多个统计与分组 [/b]

Creteria cri = session createCriteria(User.class);
ProjectionList pList = Projections.projectionList();
pList.add(Projections.max("id"));
pList.add(Projections.min("id"));

cri.setProjection(pList);

Object[] array = (Object[]) cri.uniqueResult();
System.out.println(array[0] + " : " +array[1]);

[b]排序 [/b]

Session session = HibernateUtil.getSession();
session.beginTransaction();
Criteria cri = session.createCriteria(User.class);

cri.addOrder(Order.desc("id"));
cri.addOrder(Order.asc("username"));

List<User> list = cri.list();
for(User user : list) {
System.out.println(user.getId() + " : " + user.getUsername());
}
session.getTransaction().commit();

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[b]当然也可以使用原生sql[/b]

Session session = HibernateUtil.getSession();
session.beginTransaction();

String sql = "select * from user";
SQLQuery query = session.createSQLQuery(sql);
List<Object[]> list = query.list();

for(Object[] array : list) {
System.out.println(array[0] + " : " + array[1]);
}

String sql = "select * from user";
SQLQuery query = session.createSQLQuery(sql).addEntity(User.class);
List<User> list = query.list();

for(User user : list) {
System.out.println(user.getId() + " : " + user.getUsername());
}