hi graham,
when you do nested select the way you describe then you'll end up with n + 1
sql statements.
ojb provides an optimized way to reduce the number of sql select to 2. this
is done by prefetched relationships.
suppose you have persons having n adresses. when you define the adress
relationship as prefetched, all adresses for all persons are retrieved in
ONE call.
Query query;
Criteria crit;
crit = new Criteria();
crit.addOrderByDescending("id");
crit.addOrderByAscending("geburtsDatum");
crit.addPrefetchedRelationship("konti");
query = new QueryByCriteria(Person.class, crit);
broker.getCollectionByQuery(query);
hth
jakob
----- Original Message -----
From: "Graham Lounder" <[EMAIL PROTECTED]>
To: "OJB Users List" <[EMAIL PROTECTED]>
Sent: Thursday, October 17, 2002 1:36 PM
Subject: Nested Selects
> Hey All,
>
> Is it possible to use nested selects? What is the best approach to do
this?
> In my last project I looped through results of one query, executing other
> queries. Is there a better way of doing this? Is there features in OJB
> that will do this for me? I was thinking of using the Criteria.addSQL()
and
> add my own nested select code.
>
> Any Ideas?
> Graham
>
> ============================================
> Graham Lounder
> Java Developer
> Spatial Components Division
> CARIS
> 264 Rookwood Ave
> Fredericton NB E3B-2M2
> Office 506 462-4263
> Fax 506 459-3849
> [EMAIL PROTECTED]
> http://www.spatialcomponents.com
> ============================================
>
>
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