I've looked at the source and off the top of my head (gut feeling) I
think that two oql methods should be supported. ClassicSqlOql for
mappings that can not be supported like mine. And advanced oql for
mappings that can be supported.
When two objects (A and B) with no relation to each other both contain a
reference to another instance (C) oql does not work without multiple
objects in the from clause.
Phil
Philip DONAGHY a �crit :
>
> Bruce Snyder a �crit :
> >
> > Philip DONAGHY wrote:
> >
> > > I'm just throwing this out there because I could really use a join
> > > syntax in Castor JDO. I would like to keep the select as a simple object
> > > but the from and where clauses would look something like this.
> > >
> > > SELECT Org
> > >
> > > FROM db.finaixm.OrgAuth Org,
> > > db.finaixm.OrgAuthM OrgM
> > >
> > > WHERE Org.oamOrgAuthMId = OrgM.orgAuthMId AND
> > > Org.txtName=$1
> >
> > Philip,
> >
> > This can be achieved through th euse of a correctly written mapping
> > descriptor. The odd part is that the OQL query will *not* contain an
> > explicit join because Castor's OQL engine will create the query behind
> > the scenes. Are you not able to achieve this? Please elaborate further.
> >
> > Bruce
>
> The difficulty with this can be explained by presenting our schema which
> supports temporality. Each entity can have several versions (changes to
> airport data has to be traceable). For each moment in time there can be
> one and only one valid version. Therefore for each entity there are two
> tables. A version table which contains the data, a pk (primary key), one
> or more fk (foreign keys), and the date meta data (dateStart, dateEnd,
> dateCancelled). A master table represents all the versions a pk column
> only. Therefore you have the following relationships.
>
> Ahp.pk
> Ahp.codeId
> Ahp.fk---> AhpM.pk
> /\
> ||
> Aho.AhpMfk
> Aho.fk --------> AhoM.pk
> Aho.ObsMfk
> ||
> \/
> Obs.fk--> ObsM.pk
> Obs.geoLat
> Obs.geoLong
>
> This schema shows 6 tables AirportObstacle (Aho), AirportObstacleM
> (AhoM), Obstacle (Obs), ObstacleM (ObsM), Airport (Ahp), AirportM
> (AhpM). The sql query required is :
>
> select * from Aho, AhoM,
> Obs, ObsM,
> Ahp, AhpM
> where Aho.Ahpfk = AhpM.pk and Ahp.fk = AhpM.pk and Ahp.codeId = ?
> Aho.Obsfk = ObsM.pk and Obs.fk = ObsM.pk and Obs.geoLat = ? and
> Obs.geoLong = ?
>
> In oql
>
> select Aho from Aho where Aho.AhoM.pk = Aho.fk and
> Aho.AhpM.AhpCollection.contains(Ahp where Ahp.codeId = $1) and
> Obs.ObsM.ObsCollection.contains(Obs where Obs.geoLat = $2 and
> Obs.geoLong = $3)
>
> Is this kind of Mapping possible?
>
> The oql implementation in Castor just translates to SQL. So why not
> implement joins.
>
> Sincerely,
>
> Phil
>
> > --
> > perl -e 'print
> > unpack("u30","<0G)[EMAIL PROTECTED]&5R\\"F9E<G)E=\\$\\!F<FEI+F-O;0\\`\\`");'
> >
> > The Castor Project
> > http://www.castor.org/
> >
> > Apache Geronimo
> > http://incubator.apache.org/projects/geronimo.html
> >
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