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 Post subject: Hibernate make same aliases for different joins
PostPosted: Tue Jul 05, 2016 4:47 pm 
Newbie

Joined: Tue Jul 05, 2016 4:34 pm
Posts: 1
Suppose, we have 3 entities

Code:
<hibernate-mapping>
    <class name="BEntity" table="B">
        <id name="id" column="ID"/>
    </class>
</hibernate-mapping>


Code:
<hibernate-mapping>
    <class name="AEntity" table="A" abstract="true">
        <id name="id" column="ID"/>

        <joined-subclass table="Aa" name="AaEntity">
            <key column="key"/>
            <many-to-one name="b" class="BEntity" column="B_ID"/>
        </joined-subclass>

        <joined-subclass table="Ab" name="AbEntity">
            <key column="key"/>
            <many-to-one name="b" class="BEntity" column="B_ID"/>
        </joined-subclass>
    </class>
</hibernate-mapping>


Code:
<hibernate-mapping>
    <class name="Parent" table="parent">
        <id name="id" column="ID"/>

        <many-to-one name="a" class="AEntity" column="A_ID"/>
    </class>
</hibernate-mapping>


Then, we make criteria request

Code:
Criteria criteria = session.createCriteria(Parent.class);
criteria.createAlias("a","a");
criteria.createAlias("a.b","b");
criteria.list();

And get next sql

Code:
select this_.ID as ID1_5_3_,
       this_.a_ID as a2_5_3_,
       a1_.ID as ID1_2_0_,
       a1_.B_ID as B2_2_0_,
       a1_1_.B_ID as B2_0_0_,
       a1_2_.B_ID as B2_1_0_,
       case when a1_1_.key is not null then 1 when a1_2_.key is not null then 2 when a1_.ID is not null then 0 end as clazz_0_,
       b2_.ID as ID1_3_1_,
       b2_.C_ID as C2_3_1_,
       b2_.ID as ID1_3_2_,
       b2_.C_ID as C2_3_2_
from parent this_
inner join A a1_ on this_.a_ID=a1_.ID
left outer join Aa a1_1_ on a1_.ID=a1_1_.key
left outer join Ab a1_2_ on a1_.ID=a1_2_.key
inner join B b2_ on a1_1_.B_ID=b2_.ID
inner join B b2_ on a1_2_.B_ID=b2_.ID

We can see that B table joins two times and have same name b2_. Is it bug? And how make two joins but with different name of B table. Okay?


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 Post subject: Re: Hibernate make same aliases for different joins
PostPosted: Mon Jul 11, 2016 5:11 am 
Hibernate Team
Hibernate Team

Joined: Thu Sep 11, 2014 2:50 am
Posts: 1628
Location: Romania
That's because you mapped the B entity twice:

Code:
       <joined-subclass table="Aa" name="AaEntity">
            <key column="key"/>
            <many-to-one name="b" class="BEntity" column="B_ID"/>
        </joined-subclass>

        <joined-subclass table="Ab" name="AbEntity">
            <key column="key"/>
            <many-to-one name="b" class="BEntity" column="B_ID"/>
        </joined-subclass>


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