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From Cristian Zoicas <zoi...@medialab.sissa.it>
Subject Re: How to create a join ?
Date Thu, 11 Dec 2003 13:43:38 GMT


> You are right, I figured it out just after I sent the mail, should have
> think twice before sending it :-)
>

n.p.
At the beginning I also thought that I have the solution... :)

> I don't know any way to have such a select with Torque, but you could
> probably do it with Two selects :
>
> one for
>
> T1.id_t1= T2.id_t1 AND T2.id_t3 = T3.id_t3
> and one for
> T1.id_t3 = T3.id_t3
>

Yes. This way it works but the code would become to complicated. We also
have the option to change the databse. It works  also  with an SQL UNION
( I don't know how to do it with torque :)  ) which is in fact what your
solution says.

>And then the collection of objects you wanted is the "sum" of the 2
>collections youn got this way ...
>
> Hope it helps ...
> SaM

Cristi






>
> Cristian Zoicas wrote:
>
> >On Thu, 11 Dec 2003, Samuel Le Berrigaud wrote:
> >
> >
> >
> >>You may want to have a look at this page :
> >>
> >>http://db.apache.org/torque/peers-howto.html  (at the bottom of the page)
> >>
> >>the part named "Examples" seems to be what you want ...
> >>
> >>SaM
> >>
> >>
> >
> >Thank  you anyway and without  being  offensive  but the example you
> >pointed ( shown below ) is not exactly the same thing in my opinion.
> >
> >
> >
> >>>>BEGIN EXAMPLE <<<<
> >>>>
> >>>>
> >
> >    select * from abc where (a < 1 and b > 2) or (  a > 5  and b < 3)
> >
> >    Criteria crit = new Criteria();
> >    Criteria.Criterion a1 = crit.getNewCriterion(ABC.A, 1, Criteria.LESS_THAN);
> >    Criteria.Criterion b2 = crit.getNewCriterion(ABC.B, 2, Criteria.GREATER_THAN);
> >    Criteria.Criterion a5 = crit.getNewCriterion(ABC.A, 5, Criteria.GREATER_THAN);
> >    Criteria.Criterion b3 = crit.getNewCriterion(ABC.B, 3, Criteria.LESS_THAN);
> >
> >    crit.add(a1.and(b2).or(a5.and(b3)));
> >
> >
> >
> >>>>END EXAMPLE <<<
> >>>>
> >>>>
> >
> >Here are the reasons:
> >
> >  1. the FROM caluse contains only one table.
> >  2. The getNewCriterion method allows you to add
> >         a) a column name
> >         b) a value
> >         c) a comparison statement between the column name
> >             and the value.
> >
> >     and I need a getCriterion which allows me to add :
> >         a) a column name;
> >         b) a column name;
> >         c) a comparison statement between the columns.
> >
> >     Does torque lack such a method or is it possible to do it in
> >     another way ?
> >
> >Cristian Zoicas
> >
> >
> >
> >
> >
> >
> >
> >>Cristian Zoicas wrote:
> >>
> >>
> >>
> >>>Hello all
> >>>
> >>>I've tried to figure out how to use the Criteria class in
> >>>order to obtain a statement like
> >>>
> >>>SELECT
> >>>      *
> >>>FROM
> >>>      T1, T2, T3
> >>>WHERE
> >>>      ( T1.id_t1= T2.id_t1 AND T2.id_t3 = T3.id_t3 )
> >>>      OR
> >>>      ( T1.id_t3 = T3.id_t3 )
> >>>
> >>>but I was not able to do it.
> >>>Does anybody has any solution ?
> >>>
> >>>Thank you in advance
> >>>Cristian Zoicas
> >>>
> >>>
> >>>
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> >>>
> >>>
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> >>
> >>
> >>
> >
> >
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> >
> >
>
>
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