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List:       ojb-user
Subject:    Re: Mapping Classes on Multiple Joined Tables
From:       Jakob Braeuchi <jbraeuchi () gmx ! ch>
Date:       2004-05-06 20:25:52
Message-ID: 409A9F50.2030100 () gmx ! ch
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hi charles,

this should do it:

Query q = QueryFactory.newQuery(A.class, c);
broker.getCollectionByQuery(q);

fyi there's a testcase dealing with multi-joined-tables 
InheritanceMultipleTableTest. this testcase requires the latest from repository 
to pass completely.

hth
jakob

Charles N. Harvey III wrote:

> Hello.
> The other day I embarked on a little journey by mapping classes on
> multiple joined tables.  It went really well.  I am very excited to
> see it working and to see it working so well.
> 
> One question though, and I can use the example on the site to demonstrate.
> 
> <!-- Definitions for org.apache.ojb.broker.A -->
> <class-descriptor
>        class="org.apache.ojb.broker.A"
>        table="A_TABLE">
>    <field-descriptor
>            name="id"
>            column="ID"
>            jdbc-type="INTEGER"
>            primarykey="true"
>            autoincrement="true"/>
>    <field-descriptor
>            name="someValueFromA"
>            column="VALUE_"
>            jdbc-type="INTEGER"/>
> </class-descriptor>
> 
> <class-descriptor
>        class="org.apache.ojb.broker.B"
>        table="B_TABLE">
>    <field-descriptor
>            name="id"
>            column="ID"
>            jdbc-type="INTEGER"
>            primarykey="true"
>            autoincrement="true"/>
>    <field-descriptor
>            name="someValueFromB"
>            column="VALUE_"
>            jdbc-type="INTEGER"/>
>    <reference-descriptor
>            name="super"
>            class-ref="org.apache.ojb.broker.A"
>            auto-retrieve="true"
>            auto-update="true"
>            auto-delete="true">
>        <foreignkey
>                field-ref="id"/>
>    </reference-descriptor>
> </class-descriptor>
> 
> 
> Ok.  So, I can now do this:
> 
> Criteria c = new Criteria();
> c.addEqualTo("someValueFromA", new Integer(1));
> c.addEqualTo("someValueFromB", new Integer(2));
> Query q = QueryFactory.newQuery(B.class, c);
> broker.getCollectionByQuery(q);
> 
> Which is really cool.  But, how can I select ONLY CLASSES FROM A?  Every 
> time
> I insert a B it inserts into A.  And that's how it is supposed to work.  
> But
> I also insert plain 'ol As into A.  So how can I select a collection of 
> ONLY A?
> 
> Is this possible?  I think it is but I have to do a sub query like,
> SELECT * FROM A WHERE NOT IN (SELECT ID FROM B)  Am I correct?  And, how 
> do I
> do that in OJB?
> 
> Thanks a lot for the help.
> 
> 
> Charlie
> 
> 
> 
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