On Jan 18, 2011, at 9:11 AM, Steve wrote:
> Hi all,
>
> Newbie here.
>
> I just want to execute the following sql using SqlAlchemy . But
> getting various errors.
>
> select ssf.factor,ssf.displayname,pmw.weight
> from probability_models_weights pmw
> inner join probability_models pm on pm.id = pmw.model_id
> inner join success_factors ssf on ssf.id = pmw.factor_id
> where pm.id = 6
>
> I want to execute this using session.
>
> I am using declarative base with the following auto loaded classes.
>
> class SucessFactors(WBase):
> __tablename__ = "success_factors"
> __table_args__ = {'autoload':True}
>
> class ProbabilityModels(WBase):
> __tablename__ = "probability_models"
> __table_args__ = {'autoload':True}
>
> class ProbabilityModelsWeights(WBase):
> __tablename__ = "probability_models_weights"
> __table_args__ = {'autoload':True}
>
> I tried the following but it didn't work.
>
> session.query(SucessFactors.factor,SucessFactors.displayname,ProbabilityModelsWeights.weight).
> \
> join(ProbabilityModelsWeights,ProbabilityModels,
> ProbabilityModelsWeights.model_id == ProbabilityModels.id).\
> join(ProbabilityModelsWeights,SucessFactors,
> ProbabilityModelsWeights.factor_id == SucessFactors.id).\
> filter(ProbabilityModels.id == model_id).\
> all()
query.join() is a one-argument form (it will accept two arguments in 0.7, but
thats not released yet), so here you want to be saying
query(...).select_from(ProbabiliyModelsWeights).join((ProbabiltityModels,
ProbabiltiyModelsWeights.model_id==ProbabilityModels.id)).
the select_from() accepting a mapped class is a helper that was introudced in
0.6.5. Also note the tuple form inside of join(), i.e. join((target,
onclause)) (you won't need that in 0.7). Documented at
http://www.sqlalchemy.org/docs/orm/tutorial.html#querying-with-joins .
>
> Thanks in advance.
>
> Steve.
>
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