计算 Hibernate JPA 中子查询返回的行数

Question

I want to do something like the below query in Hibernate JPA.

select distinct count(*)
from (
         select distinct entity1.CODE                              as col_0_0_,
                         string_agg(entity2.PRODUCT_IMAGE_URL, ',') as col_1_0_,
                         count(entity1.CODE)                       as col_2_0_
         from entity1
                  inner join entity2 on entity1.id = entity2.entity1_ID                 
         where entity1.id = 1           
         group by entity1.CODE
     ) as cnt;

Any idea how would i do this using Criteria API?

Answer 1

You will need something like the following:

CriteriaBuilder cb = entityManager.getCriteriaBuilder();
CriteriaQuery<Long> criteriaQuery = cb.createQuery(Long.class);
Root<Entity1> root = criteriaQuery.from(MyEntity.class);
criteriaQuery.select(criteriaBuilder.countDistinct(entityRoot.get("code")));
Long count = entityManager.createQuery(criteriaQuery).getSingleResult();