java - 如何在类型化查询中制定JOIN？

我想创建一个类型查询。

TypedQuery<PubThread> query = em.createQuery(queryString, PubThread.class);
query.setParameter("threadId", threadId);
List<PubThread> otherPubThreads = query.getResultList();

在queryString中是以下SQL（当前没有参数和静态选择值）

SELECT pt2 FROM pubthread pt2
JOIN pub_pubthread ppt2 ON pt2.id = ppt2.pubThreads_id
JOIN pub p2 ON ppt2.pups_id = p2.id
JOIN pubcategory pc2 ON p2.pubCategoryId = pc2.id
WHERE pt2.id != 1 and EXISTS (
    SELECT DISTINCT(pt.id)
    FROM pubthread pt
    JOIN pub_pubthread ppt ON pt.id = ppt.pubThreads_id
    JOIN pub p ON ppt.pups_id = p.id
    JOIN pubcategory pc ON p.pubCategoryId = pc.id
    WHERE pc2.id = pc.id and pt.id = 1
)

如果我将String限制为一个简单的选择，它确实可以工作：SELECT Distinct(pt2.id), pt2.name FROM pubthread pt2。一旦我向其中添加JOIN行，它就会抱怨。如何在JPA中使用JOINS正确查询？错误是：
org.hibernate.hql.internal.ast.QuerySyntaxException: unexpected token: ON near line 1, column 81 [SELECT pt2 FROM com.brayan.webapp.model.PubThread pt2 JOIN pub_pubthread ppt2 ON pt2.id = ppt2.pubThreads_id ]

毫无疑问，条件查询会更好。我接受这作为解决方案空间的一部分。

最佳答案

得到它了。请参见下面的完整连接示例。它包括：


多个联接（联接链接）
子查询
联接表（而不是根表）上的谓词相关性/等式。


我还评论了其他人的过时代码行，以查看哪种方法错误。

CriteriaBuilder条件Builder = em.getCriteriaBuilder（）;
        CriteriaQuery mainQuery =条件构建器
                .createQuery（PubThread.class）;

    // 1) MainQuery
    // Create the FROM
    Root<PubThread> rootPubThread = mainQuery.from(PubThread.class);
    // Create the JOIN from the first select: join-chaining. You only need the return for ordering. e.g. cq.orderBy(cb.asc(categoryJoin.get(Pub_.title)));
    Join<Pub, PubCategory> categoryJoin = rootPubThread.join(PubThread_.pups).join(Pub_.pubCategory);
    // Create the WHERE
    mainQuery.where(criteriaBuilder.not(criteriaBuilder.equal(rootPubThread.get(PubThread_.id), threadId)));
    // Create the SELECT, at last
    mainQuery.select(rootPubThread).distinct(true);

    // 2) Subquery
    Subquery<PubThread> subquery = mainQuery.subquery(PubThread.class);
    Root<PubThread> rootPubThreadSub = subquery.from(PubThread.class);
    //subquery.where(criteriaBuilder.equal(rootPubThread.get(PubThread_.id), threadId));
    Join<Pub, PubCategory> categoryJoinSub = rootPubThreadSub.join(PubThread_.pups).join(Pub_.pubCategory);
    subquery.select(rootPubThreadSub);

    //Predicate correlatePredicate = criteriaBuilder.equal(rootPubThreadSub.get(PubThread_.id), rootPubThread);
    Predicate correlatePredicate = criteriaBuilder.and(
            //criteriaBuilder.equal(rootPubThreadSub.get(PubThread_.id), rootPubThread),
            criteriaBuilder.equal(categoryJoinSub.get(PubCategory_.id), categoryJoin.get(PubCategory_.id)),

            criteriaBuilder.equal(rootPubThreadSub.get(PubThread_.id), threadId)
            );
    subquery.where(correlatePredicate);

    //Predicate correlatePredicate = criteriaBuilder.equal(rootPubThreadSub.get(PubThread_.id), rootPubThread);
    Predicate mainPredicate = criteriaBuilder.and(
            criteriaBuilder.not(criteriaBuilder.equal(rootPubThread.get(PubThread_.id), threadId)),
            criteriaBuilder.exists(subquery)
            );
    //cq.where(criteriaBuilder.exists(subquery));
    mainQuery.where(mainPredicate);