java - 使用 hibernate 无法获取完整数据

Question

以下是我的实体结构；

class Question{}
class Answer {
    @ManyToOne
    Question q;
}
class Comment {
    @ManyToOne
    Answer a;
}

为了通过 QuestionId 获取问题的所有详细信息，我使用查询得到以下结果

select * from Comment c 
right join Answer a on c.answer_id = a.id 
right join Question q on a.question_id = q.id
where q.id = 27
order by a.likes desc;

[有六行]

'10', '2016-05-16 11:41:22', '0', 'I use pink so it should be pink.', '0', '2016-05-16 11:43:43', '0', '0', '1', NULL, '16', '159', NULL, NULL, '16', '2', '2016-05-16 11:33:51', '0', 'I use black so it should be black', '2', '2016-05-16 11:37:24', '0', '1', '2016-05-16 12:10:32', '146', NULL, '27', NULL, '27', '4', '2016-05-16 11:30:28', '2016-05-16 11:31:01', '0', 'What is most preferred color', '9', '1', NULL, '2016-05-16 12:10:32', '146', NULL, NULL
'11', '2016-05-16 11:41:45', '0', 'What about CYAN. :p', '0', '2016-05-16 11:43:43', '0', '0', '1', NULL, '16', '159', NULL, NULL, '16', '2', '2016-05-16 11:33:51', '0', 'I use black so it should be black', '2', '2016-05-16 11:37:24', '0', '1', '2016-05-16 12:10:32', '146', NULL, '27', NULL, '27', '4', '2016-05-16 11:30:28', '2016-05-16 11:31:01', '0', 'What is most preferred color', '9', '1', NULL, '2016-05-16 12:10:32', '146', NULL, NULL

'8', '2016-05-16 11:39:00', '0', 'And those factors are??', '0', '2016-05-16 11:43:42', '0', '0', '1', NULL, '15', '159', NULL, NULL, '15', '2', '2016-05-16 11:33:28', '0', 'This depends on many factors. Start noticing different mobile phones.', '1', '2016-05-16 11:37:24', '0', '1', '2016-05-16 12:10:03', '146', NULL, '27', NULL, '27', '4', '2016-05-16 11:30:28', '2016-05-16 11:31:01', '0', 'What is most preferred color', '9', '1', NULL, '2016-05-16 12:10:32', '146', NULL, NULL
'9', '2016-05-16 11:40:28', '0', 'Color of the SUN', '0', '2016-05-16 11:43:43', '0', '0', '1', NULL, '15', '159', '8', NULL, '15', '2', '2016-05-16 11:33:28', '0', 'This depends on many factors. Start noticing different mobile phones.', '1', '2016-05-16 11:37:24', '0', '1', '2016-05-16 12:10:03', '146', NULL, '27', NULL, '27', '4', '2016-05-16 11:30:28', '2016-05-16 11:31:01', '0', 'What is most preferred color', '9', '1', NULL, '2016-05-16 12:10:32', '146', NULL, NULL

NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, '17', '0', '2016-05-16 11:34:55', '0', 'Not every company manufactures yellow mobile phone.', '1', '2016-05-16 11:37:24', '0', '1', '2016-05-16 12:10:18', '146', NULL, '27', NULL, '27', '4', '2016-05-16 11:30:28', '2016-05-16 11:31:01', '0', 'What is most preferred color', '9', '1', NULL, '2016-05-16 12:10:32', '146', NULL, NULL

'12', '2016-05-16 11:42:15', '0', 'Thought Well', '0', '2016-05-16 11:43:43', '0', '0', '1', NULL, '18', '159', NULL, NULL, '18', '1', '2016-05-16 11:35:32', '0', 'It is similar to color of the cars you see on the road.', '0', '2016-05-16 11:37:24', '0', '1', '2016-05-16 11:43:27', '146', NULL, '27', NULL, '27', '4', '2016-05-16 11:30:28', '2016-05-16 11:31:01', '0', 'What is most preferred color', '9', '1', NULL, '2016-05-16 12:10:32', '146', NULL, NULL

因此，通过这样做，我还获得了评论数为零的答案的数据。但是当我将 hibernate 与 HQL 结合使用时

SELECT c FROM Comment c 
RIGHT OUTER JOIN c.answer a 
RIGHT OUTER JOIN a.question q
where q.id = :questionId";

我只得到 5 行，因此我错过了那些没有评论的答案。请帮助我得到答案。

Answer 1

在这种情况下，您也可以很好地编写命名查询，因为您的 sql 工作正常。

String sql = "select * from Comment c 
              right join Answer a on c.answer_id = a.id 
              right join Question q on a.question_id = q.id
              where q.id = :questionId
              order by a.likes desc";

SQLQuery query = session.createSQLQuery(sql);
query.addEntity(Object.class);
query.setParameter("questionId", id);
List results = query.list();