sql的join语句转成hql出现的问题

最新推荐文章于 2020-09-06 20:38:51 发布

王奕然

最新推荐文章于 2020-09-06 20:38:51 发布

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分类专栏： Hibernate

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本文探讨了在Hibernate中使用HQL实现特定SQL JOIN语句的挑战，包括如何正确地构造左连接，并解决了生成SQL与预期不符的问题。

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我用sql语句写出了一条join语句

select distinct m.name from messagebox m inner join reply r on m.getperson_id = r.send_reply_person_id where r.send_reply_person_id=1 union
select m.name from messagebox m where m.sendperson_id=1;

但是想写成hql的时候遇到了问题，

我试了很多hql语句，比如

		//Query query = getSession().createQuery(" from Reply as o left join o.getPerson join ");

他总是生成诸如

SELECT * FROM 表A LEFT JOIN 表B ON 表A.字段12(主键) = 表B.字段1(<set>中key的值)

比如

Hibernate: select messagebox0_.id as id1_0_, replies1_.id as id2_1_, messagebox0_.name as name1_0_, messagebox0_.content as content1_0_, messagebox0_.sendTime as sendTime1_0_, messagebox0_.sendPerson_id as sendPerson5_1_0_, messagebox0_.getPerson_id as getPerson6_1_0_, messagebox0_.collect as collect1_0_, messagebox0_.canBeReplied as canBeRep8_1_0_, messagebox0_.rubbish as rubbish1_0_, replies1_.title as title2_1_, replies1_.content as content2_1_, replies1_.PARENT_REPLY_ID as PARENT4_2_1_, replies1_.MESSAGEBOX_ID as MESSAGEBOX5_2_1_, replies1_.SEND_REPLY_PERSON_ID as SEND6_2_1_, replies1_.SEND_REPLY_TIME as SEND7_2_1_ from MessageBox messagebox0_ left outer join reply replies1_ on messagebox0_.id=replies1_.MESSAGEBOX_ID

我的hbm.xml

	<class name="MessageBox" table="MessageBox">
		<id name="id"  type="string" column="id">
		<generator class="uuid"></generator>
</id>
		  <set name="replies" lazy="false"  inverse="true">
        <key column="MESSAGEBOX_ID"/>
        <one-to-many class="Reply"/> 
    </set>

我需要改成SELECT * FROM 表A LEFT JOIN 表B ON 表A.字段12(非主键,且任意由自己定) = 表B.字段1(任意)

于是我在网上查看，有个兄弟遇到了同样的问题，但也没用解决好。他的问题：http://bbs.youkuaiyun.com/topics/260028474

所以改用了sqlQuery