# 15.8\. 離線(detached)查詢和子查詢 `DetachedCriteria`類使你在一個session范圍之外創建一個查詢，并且可以使用任意的 `Session`來執行它。 ``` 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詢。條件實例包含子查詢可以通過 `Subqueries`或者`Property`獲得。 ``` 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(); ``` 甚至相互關聯的子查詢也是有可能的： ``` 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(); ```