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 Post subject: Joining tables, mapping
PostPosted: Wed Mar 08, 2006 5:18 pm 
Newbie

Joined: Wed Mar 08, 2006 5:08 pm
Posts: 1
Hibernate 3.0

I am involved in a project where the database, tables are already created. The tables I am dealing with currently include simple joins between two or three tables to gather data. I cannot change this fact.

Since I have existing data, which approach do I use? I have read and cannot figure this out:
Table per concrete class?
Table per class hierarchy?
Table per subclass?

So let say table per subclass. If I am joining on two tables. Lets say foo and baz. Where foo.id is a primary key and baz.id is the foreign key.

When I create my mappings, do I create two mappings? I cannot seem to find examples of this type of join.

Then if I create two mappings, and two classes to hold the data in, then do I issue a hql query that joins the tables?

If someone could give me some starter points here, I would certainly appreciate.


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 Post subject:
PostPosted: Thu Mar 09, 2006 7:08 pm 
Beginner
Beginner

Joined: Thu Jun 30, 2005 5:07 am
Posts: 33
First, you do not need to create hql in order to create the join table.
the join table will be created from the xx.hbm.xml files for example:
in Foo.hbm.xml file write something like that:
<set
name="associatedBaz"
table="foo_baz"
lazy="false"
cascade="save-update"
sort="unsorted"
>

<key
column="Foo_ID"
>
</key>

<many-to-many
class="com.mycompan.Baz"
column="Baz_ID"
outer-join="auto"
/>

</set>

in Baz.hbm.xml write something like:
<set
name="supportedFoo"
table="foo_baz"
lazy="false"
inverse="true"
cascade="save-update"
sort="unsorted"
>

<key
column="baz_ID"
>
</key>

<many-to-many
class="com.mycompany.Foo"
column="foo_ID"
outer-join="auto"
/>

</set>


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