java - 将 HQL 子查询转换为 Criteria

Question

我想翻译这个HQL的结构:

FROM Entity_1 obj
WHERE obj IN (FROM Entity2) OR 
      obj IN (FROM Entity3)

如何实现？

Answer 1

它在 Hibernate 标准文档中有解释:http://docs.jboss.org/hibernate/core/3.3/reference/en/html/querycriteria.html#querycriteria-detachedqueries

DetachedCriteria 也可用于表示子查询。涉及子查询的Criterion实例可以通过Subqueries或Property获取。

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();

相关子查询也是可能的:

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();