Criteria objects will replace SQL in all but the most extreme cases. Take
another look at the Peers Howto
(http://db.apache.org/torque/peers-howto.html), specifically in the "Joins
And Linking Objects" section. I will repeat the concept below because
sometimes it helps to hear it another way...
If you simply want to pull a field from a related object, use the
<foreign-key> tag in your schema to relate them. When generating your peers
and classes, this will provide a get<RelatedObject>() or
get<RelatedObject>s() in the objects which you can use to access the foreign
object, and thus the foreign field.
For example, I have a Customer and a BuilderRegistration. BR's are related
to C's by CUSTOMER_ID. Say I want the name of the customer that registered
a particular builder:
Schema:
=================================================================
<table name="BUILDER_REGISTRATION">
...
<foreign-key foreignTable="CUSTOMER">
<reference local="CUSTOMER_ID" foreign="CUSTOMER_ID"/>
</foreign-key>
</table>
Criteria:
=================================================================
Criteria crit = new Criteria();
crit.add(BuilderRegistrationPeer.ID,builderRegId);
Usage:
=================================================================
List results = BuilderRegistrationPeer.doSelect(crit);
BuilderRegistration breg = (BuilderRegistration)results.get(0);
System.out.println("BREG " + builderRegId + " belongs to Customer " +
breg.getCustomer().getName());
I hope this helps,
Chris
> From: goffredo
>
> I have been reading the documentation on using Criteria objects
> with Torque,
> but can't find an example of a join of say three or four tables
> that returns
> all the columns of the three or four tables that satisfy the
> conditions of the
> query. The examples illustrate multiple joins, but retrieve
> information from
> only one of the tables in the join, because the doSelect() method
> is attached
> to Peer classes only. Or am I expected to add tables to my
> database to handle
> this kind of situation?
>
> I am not sure from reading the documentation if the use of
> Criteria is designed
> to replace SQL ... or if Criteria form a more limited subset of SQL.
>
> Regards
> Goffredo
---------------------------------------------------------------------
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]
