在我们的搜索之后，我仍然无法找到在 EclipseLink条件查询中编写此SQL等效项的方法：
SELECT preke.*, count(nuotrauka.prid) AS cnt FROM preke LEFT JOIN nuotrauka ON nuotrauka.prid=preke.prid WHERE trash = 1 GROUP BY preke.prid ORDER BY cnt DESC
我尝试了加入，多选等等。我需要getResultList()在List List内回复list[0] - (Preke)preke1, list[1] - (Integer)count1; list[0] - (Preke)preke2, list[1] - (Integer)count2 ...，如CriteriaBuilder cb = EntityManager.getInstance().getCriteriaBuilder();
CriteriaQuery criteriaQuery = cb.createQuery(Tuple.class);
Root<Preke> from = criteriaQuery.from(Preke.class);
Expression<Long> count = cb.count(from.get("images"));
criteriaQuery.where(cb.equal(from.get("trash"), true));
criteriaQuery.multiselect(from.alias("preke"), count.alias("count"));
criteriaQuery.groupBy(from.get("prid"));
TypedQuery<Tuple> typedQuery = EntityManager.getInstance().createQuery(criteriaQuery);
typedQuery.setFirstResult(PAGE * ITEMS_PER_PAGE);
typedQuery.setMaxResults(ITEMS_PER_PAGE);
prekes = typedQuery.getResultList();
...
for(Tuple t : prekes) {
Preke p = (Preke)t.get("preke");
long count = (long)t.get("count");
...
}
。
编辑1 ：
SELECT t0.prid AS a1,
...,
COUNT(t1.id)
FROM preke t0,
nuotrauka t1
WHERE
((t0.trash = ?) AND (t1.prid = t0.prid))
GROUP BY t0.prid LIMIT ?, ?
它给我以下JPQL语句：
t1.prid = t0.prid这几乎没问题，但它不包括count为0的结果。
正如上面的JPQL声明所说 - LEFT JOIN应该是不好的部分，如何替换它？我想我需要的是{{1}}。但是怎么做呢？
答案 0 :(得分：1)
而不是使用
Expression<Long> count = cb.count(from.get("images"));
尝试使用
Join<Preke, Nuotrauka> images = from.join("images", JoinType.LEFT);
Expression<Long> count = cb.count(images);