Re: Mapping Classes on Multiple Joined Tables

[Jakob Braeuchi]

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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