On Sep 17, 2010, at 7:50 AM, sajuptpm wrote:
>
> DBSession.query(func.length(class_name.cpu_util),
> (DBSession.query(func.variance(class_name.util)).\
>
> filter(class_name.entity_id==entity_id).filter(class_name.metric_type==metric_type).
> \
>
> filter(class_name.cdate>=from_date).filter(class_name.cdate<=to_date).all()),
> \
> func.avg(class_name.m_util)).\
>
> filter(class_name.entity_id==entity_id).filter(class_name.metric_type==metric_type).
> \
>
> filter(class_name.cdate>=from_date).filter(class_name.cdate<=to_date).all()
all() executes the SQL and returns a list, not a subquery. You would need to
remove the call to .all() from your subquery.
to label the subquery, session.query(...).subquery().label('foo').
>
>
> ERROR
> ======
> File "/root/tg2env/lib/python2.4/site-packages/SQLAlchemy-0.5.6-
> py2.4.egg/sqlalchemy/orm/scoping.py", line 123, in do
> return getattr(self.registry(), name)(*args, **kwargs)
> File "/root/tg2env/lib/python2.4/site-packages/SQLAlchemy-0.5.6-
> py2.4.egg/sqlalchemy/orm/session.py", line 895, in query
> return self._query_cls(entities, self, **kwargs)
> File "/root/tg2env/lib/python2.4/site-packages/SQLAlchemy-0.5.6-
> py2.4.egg/sqlalchemy/orm/query.py", line 92, in __init__
>
> self._set_entities(entities)
> File "/root/tg2env/lib/python2.4/site-packages/SQLAlchemy-0.5.6-
> py2.4.egg/sqlalchemy/orm/query.py", line 99, in _set_entities
> entity_wrapper(self, ent)
> File "/root/tg2env/lib/python2.4/site-packages/SQLAlchemy-0.5.6-
> py2.4.egg/sqlalchemy/orm/query.py", line 2099, in __init__
> raise sa_exc.InvalidRequestError(
> InvalidRequestError: SQL expression, column, or mapped entity expected
> - got '[(0.0,)]'
>
>
>
>
> Here i am using a subquery to find variance. How give a name to
> subquery result column.
> (DBSession.query(func.variance(class_name.util)).\
>
> filter(class_name.entity_id==entity_id).filter(class_name.metric_type==metric_type).
> \
>
> filter(class_name.cdate>=from_date).filter(class_name.cdate<=to_date).all())
>
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