java认证:Hibernate高级查询技巧

http://www.webjx.com/  2009-06-09 16:04:01  来源:网页教学网 

Webjx网页教学提示: 1: QBE (Query By Example) Criteria cri = session.createCriteria(Student.class);cri.add(Example.create(s)); //s是一个Student对象list cri.list();

  1: QBE (Query By Example)

  Criteria cri = session.createCriteria(Student.class);cri.add(Example.create(s)); //s是一个Student对象list cri.list();

  实质:创建一个模版,比如我有一个表serial有一个 giftortoy字段,我设置serial.setgifttoy("2"),

  则这个表中的所有的giftortoy为2的数据都会出来

  2: QBC (Query By Criteria) 主要有Criteria,Criterion,Oder,Restrictions类组成

  session = this.getSession();Criteria cri = session.createCriteria

  (JdItemSerialnumber.class);Criterion cron = Restrictions.like

  ("customer",name);cri.add(cron);list = cri.list();

  比较运算符

  HQL运算符 QBC运算符 含义

  =Restrictions.eq()等于

  <> Restrictions.not(Exprission.eq()) 不等于

  >Restrictions.gt()大于

  >= Restrictions.ge()大于等于

  <= Restrictions.le()小于等于

  is null Restrictions.isnull() 等于空值

  is not nullRestrictions.isNotNull() 非空值

  like Restrictions.like() 字符串模式匹配

  and Restrictions.and() 逻辑与

  and Restrictions.conjunction()逻辑与

  or Restrictions.or()逻辑或

  or Restrictions.disjunction()逻辑或

  notRestrictions.not() 逻辑非

  in(列表) Restrictions.in()等于列表中的某一个值

  ont in(列表)Restrictions.not(Restrictions.in())不等于列表中任意一个值

  between x and yRestrictions.between() 闭区间xy中的任意值

  not between x and y Restrictions.not(Restrictions..between()) 小于值X或者大于值y

  3: HQL

  String hql = "select s.name ,avg(s.age) from Student s group by s.name";Query query = session.createQuery(hql);list = query.list();....

  4: 本地SQL查询 session = sessionFactory.openSession();tran = session.beginTransaction();SQLQuery sq = session.createSQLQuery(sql);sq.addEntity(Student.class);list = sq.list();tran.commit();

  5: QID

  Session的get()和load()方法提供了根据对象ID来检索对象的方式。该方式被用于事先知道了要检索对象ID的情况。

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