条件查询：按数量排序

Criteria criteria = session.createCriteria(Question.class, "q");criteria.createAlias("q.answers", "answer", Criteria.LEFT_JOIN);criteria.setProjection(Projections.projectionList().add(Projections.groupProperty("q.id"))       .add(Projections.count("answer.id").as("numberOfAnswers")));criteria.addOrder(Order.desc("numberOfAnswers"));

这将返回一个Object []列表。每个Object []都将问题的ID作为第一个元素，并将此问题的答案数目作为第二个元素。问题按答案的降序排列。

如果你需要额外的属性（例如：问题文本），然后添加其他groupProperty预测（例如：

add(Projections.groupProperty("q.text"))

与此条件查询对应的SQL如下所示：

select this_.ID_QUESTION as y0_, count(answer1_.ID_ANSWER) as y1_ from QUESTION this_ left outer join ANSWER answer1_ on this_.ID_QUESTION=answer1_.ID_QUESTION group by this_.ID_QUESTION order by y1_ desc;