将HQL子查询转换为Criteria

Question

我想翻译这个HQL结构：

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

怎么做？

Answer 1

Hibernate标准文档中解释了这一点：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。涉及子查询的标准实例可以通过子查询或属性获得。

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();

相关的子查询也是可能的：

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();

Answer 2

我对HQL很新，但我建议如下：

 DetachedCriteria sub1 = DetachedCriteria.forClass(Entitiy2);
 DetachedCriteria sub2 = DetachedCriteria.forClass(Entity3);

 Criteria criteria = getYourSession().createCriteria(Entity_1.class, "obj");
 criteria.add(Restrictions.or(Subqueries.propertyIn("obj", sub1), Subqueries.propertyIn("obj", sub2));

如果我错了，请纠正我。