Hibernate子查询detachedCriteria

Question

如何在hibernate中编写一个包含多个子查询的子查询。例如

select * from project_dtls where project_id in  
  (select project_id from project_users where user_id =
  (select user_id from user_dtls where email='abc@email.com'))

我知道我们可以通过DetachedCriteria编写代码，但是找不到任何可以使用多个子查询的例子。

Answer 1

下面是一个例子：

DetachedCriteria exampleSubquery = DetachedCriteria.forClass(MyPersistedObject.class)
    .setProjection(Property.forName("id"))
    // plus any other criteria...
    ;

Criteria criteria = getSession().createCriteria(ARelatedPersistedObject.class)
    .setResultTransformer(Criteria.DISTINCT_ROOT_ENTITY)
    .add(Subqueries.propertyIn("myPersistedObjectId", exampleSubquery)));

对于多个子查询，可以使用像Restrictions.or()这样的布尔运算符：

DetachedCriteria anotherSubquery = DetachedCriteria.forClass(MyPersistedObject.class)
    .setProjection(Property.forName("id"))
    // plus any other criteria...
    ;

Criteria criteria = getSession().createCriteria(ARelatedPersistedObject.class)
    .setResultTransformer(Criteria.DISTINCT_ROOT_ENTITY)
    .add(Restrictions.or(
        Subqueries.propertyIn("myPersistedObjectId", exampleSubquery),
        Subqueries.propertyIn("myPersistedObjectId", anotherSubquery)));

Answer 2

完全使用分离的标准(因为我喜欢在没有会话的情况下构造分离的标准)

DetachedCriteria idQuery = DetachedCriteria.forClass(MyPersistedObject.class)
    .setProjection(Property.forName("id"))
DetachedCriteria recordQuery = DetachedCriteria.forClass(MyPersistedObject.class)
    .add(Property.forName("id").eq(idQuery) );