JPA Criteria API 加入

Question

我如何将此 JPQL 查询转换为 Criteria API？

select count(p) from Person p join p.glanceList g where p.duration < 1000 and g
.duration < 1000

Answer 1

试试这个。

CriteriaQuery<Long> q = cb.createQuery(Long.class);
Root<Person> person = q.from(Person.class);
Join<Person,Glance> glance = person.join("glanceList", JoinType.INNER);
q.select(cb.count(person))
.where(cb.lt(person.get("duration"), 1000), cb.lt(glance.get("duration"), 1000));

假设 Glance 是连接中实体的类。

和

CriteriaBuilder cb = em.getCriteriaBuilder();