用于加入子查询的JPA CriteriaBuilder

用于加入子查询的JPA CriteriaBuilder

我认为解决方案比看起来简单。您忘记了包含

cb.max ()

在CriteriaBuilder子查询中。以下代码执行您要查找的查询。

final CriteriaBuilder cb = entityManager.getCriteriaBuilder();final CriteriaQuery<Person> cq = cb.createQuery(Person.class);final Root<Person> root = cq.from(Person.class);cq.select(root);final Subquery<Integer> subquery = cq.subquery(Integer.class);final Root<Person> validityIDSQ = subquery.from(Person.class);subquery.select(cb.max(validityIDSQ.get(Person_.validityID)));subquery.groupBy(validityIDSQ.get(Person_.personID));cq.where(cb.in(root.get(Person_.validityID)).value(subquery));

此代码将创建以下查询：

select    person0_.id as id1_0_,    person0_.personID as personID2_0_,    person0_.validityID as validity3_0_,    person0_.value as value4_0_from    person person0_where    person0_.validityID in ( select     max(person1_.validityID) from     person person1_ group by     person1_.personID)

我认为您正在使用Postgres。没有

cd.max()

它会产生您引用的错误，因为您使用GroupBy而不使用聚合函数。我在Postgres和MySQL上进行了测试。两者兼具魅力。