# 15.8\. 离线(detached)查询和子查询 `DetachedCriteria`类使你在一个session范围之外创建一个查询，并且可以使用任意的 `Session`来执行它。 ``` DetachedCriteria query = DetachedCriteria.forClass(Cat.class) .add( Property.forName("sex").eq('F') ); Session session = ....; Transaction txn = session.beginTransaction(); List results = query.getExecutableCriteria(session).setMaxResults(100).list(); txn.commit(); session.close(); ``` `DetachedCriteria`也可以用以表示子查询。条件实例包含子查询可以通过 `Subqueries`或者`Property`获得。 ``` DetachedCriteria avgWeight = DetachedCriteria.forClass(Cat.class) .setProjection( Property.forName("weight").avg() ); session.createCriteria(Cat.class) .add( Property.forName("weight).gt(avgWeight) ) .list(); ``` ``` DetachedCriteria weights = DetachedCriteria.forClass(Cat.class) .setProjection( Property.forName("weight") ); session.createCriteria(Cat.class) .add( Subqueries.geAll("weight", weights) ) .list(); ``` 甚至相互关联的子查询也是有可能的： ``` DetachedCriteria avgWeightForSex = DetachedCriteria.forClass(Cat.class, "cat2") .setProjection( Property.forName("weight").avg() ) .add( Property.forName("cat2.sex").eqProperty("cat.sex") ); session.createCriteria(Cat.class, "cat") .add( Property.forName("weight).gt(avgWeightForSex) ) .list(); ```