Aren't you supposed to do something like:
select A.a, A.b, A.B.c, A.C.d, A.C.D.e, A.C.D.f from A,B,C,D;
???
And THE BIG question is... when you perform an OQLQuery.execute() this
returns and Object what critery should I follow to choose the container
to store the resulting objects?
On Thu, 2004-07-01 at 19:49, Auckyboy wrote:
> I'll take a stab at it.
>
> when performing OQL queries using OJB, you get back the complete object
> A with references to B, C and further objects if they exist otherwise
> they are null.
>
> Assuming you have the following objects..
>
> A{
> B b;
> int bId;
> C c;
> int cId;
> }
>
> and
>
> C{
> D d;
> int dId;
> }
>
>
> D{
> id;
> name;
> }
> Now you want A where B, C and D are defined...
>
> select a from A where bID != 0 and cId!=0 and c.dId!=0
>
> this in effect would give you A where B,C and D are defined.
>
> However, as a suggestion, if you need to perform queries on A, B, C
> etc..its better to use...
>
> select a from A where c.d.name = "somename"
>
>
> HTH
> -A
>
> On Thu, 2004-07-01 at 10:19, Martin I. Levi wrote:
> > Hi!
> >
> > Well, here I am with the ODMG 3.0 book trying to perform OQL querys
> > through OJB but I really think I just dont get it.
> > Lets suppose I have a table A with FK to B and C where C has a FK to D
> > Something like this:
> > B
> > /
> > A
> > \
> > C
> > \
> > D
> >
> > Which are mapped to the objects A, B, C and D.
> > Now I want to perform a query which in SQL would be:
> >
> > SELECT A.a, A.b, B.c, C.d, D.e, D.f
> > FROM A,B,C,D
> > WHERE A.B_key = B.B_key
> > AND A.C_key = C.C_key
> > AND C.D_key = D.D_key
> > ;
> >
> > My questions are...
> > 1) how could I do this on an OQL query through OJB?
> > 2) which kind of container should I use to store the result? An
> > ArrayList does always do the trick?, I suppose it doesn't...
> >
> > Any help will be useful!
> >
> > --
> > Saludos,
> >
> > Martin I. Levi
> >
> > Centre Tecnol�gic de Transferenci�ncia de Calor
> > Universitat Polit�cnica de Catalunya
> > www.cttc.upc.edu
> >
> >
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> >
>
>
>
>
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--
Saludos,
Martin I. Levi
Centre Tecnol�gic de Transferenci�ncia de Calor
Universitat Polit�cnica de Catalunya
www.cttc.upc.edu
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