[sqlalchemy] Re: How to refer to fields in nested queries?

2015-12-08 Thread Jonathan Vanasco 
If you don't use a subquery, you can use the `desc("column")` in 
`sqlalchemy`.  (there is an `asc()` as well).  Below I use `label('name')` 
to specify the result column name for computed field, then order by it.

results = dbSession.query(
   model.Foo.a,
   sqlalchemy.func.count(Model.Foo.b).label('count_b')
 )\
 .group_by(model.Foo.a)\
 .order_by(sqlalchemy,desc('count_b')\
 .all()

If you are using a subquery for additional processing or joins, you can use 
`label()` to specify the name for the computed column, then access that 
column as an attribute on the `.c` columns attribute of the subquery 
object.  

inner_query = dbSession.query(
   model.Foo.a,
   sqlalchemy.func.count(Model.Foo.b).label('count_b')
 )
 inner_query = inner_query.subquery('query_foo')
 results = 
dbSession.query(inner_query.c.count_b.label('count_results')).all()

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[sqlalchemy] Re: How to refer to fields in nested queries?

2015-12-08 Thread SF Markus Elfring 
> If you are using a subquery for additional processing or joins,
> you can use `label()` to specify the name for the computed column,
> then access that column as an attribute on the `.c` columns attribute of the 
> subquery object.

Thanks for your information.


> inner_query = dbSession.query(
>model.Foo.a,
>sqlalchemy.func.count(Model.Foo.b).label('count_b')
>  )
>  inner_query = inner_query.subquery('query_foo')
>  results = 
> dbSession.query(inner_query.c.count_b.label('count_results')).all()

Another part of the desired data analysis is working here now.

Will it become easier to recognise the relevant relationships
from the corresponding programming interface documentation?

Regards,
Markus

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[sqlalchemy] Re: How to refer to fields in nested queries?

2015-12-08 Thread Jonathan Vanasco 


On Tuesday, December 8, 2015 at 12:14:46 PM UTC-5, SF Markus Elfring wrote:
>
> Will it become easier to recognise the relevant relationships 
> from the corresponding programming interface documentation? 
>

You should read through the tutorial/narrative documentation on the ORM and 
"Core", as well as the FAQ.  That will familiarize you a lot with where to 
find the information.

The SqlAlchemy library is incredibly robust and large; even after years of 
usage people find new features.

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