Glauco wrote:
> Michael Bayer ha scritto:
>
>>
>> On Mar 14, 2007, at 12:49 PM, Glauco wrote:
>>
>>> This is perfect but when i try to use count function the SQL
>>> composer try to do an expensive sql.
>>>
>>>
>>> In [63]: print select([tbl['azienda'].c.id], tbl['azienda']).count()
>>> *SELECT count(id) AS tbl_row_count
>>> FROM (SELECT azienda.id AS id
>>> FROM azienda)*
>>>
>>
>> what makes you think that query is expensive ? anyway, more succinct
>> to just say table.count().
>
> because i expect that engine do a SELECT COUNT FROM BLABLA and no a
> SELECT COUNT FROM ( SELECT BLABLA)
> i think this is expensive for my DataBase.
>
> in this example i've used a simple table but this is a complex qry so
> i cannot use tbl.count()
>
>
>
>>
>>>
>>> Another question:
>>>
>>> Does anyone know how to use this object ?
>>>
>>> select([tbl['azienda'].c.id], tbl['azienda']).count()
>>> <sqlalchemy.sql.Select object at 0xb6c803ac>
>>>
>>
>> select(...).count().execute()
>>
>> or
>>
>> engine.connect().execute(select(...).count())
>>
>>
>>
> I've done a lot of try.... this don't work....
>
> print select([tbl['azienda'].c.id], tbl['azienda']).execute()
>
>
> *In [8]: print select([tbl['azienda'].c.id],
> tbl['azienda']).count().execute()*
> 2007-03-15 09:51:29,870 sqlalchemy.engine.base.Engine.0x..d4 INFO
> SELECT count(id) AS tbl_row_count
> FROM (SELECT azienda.id AS id
> FROM azienda)
> 2007-03-15 09:51:29,870 sqlalchemy.engine.base.Engine.0x..d4 INFO {}
> 2007-03-15 09:51:29,871 sqlalchemy.engine.base.Engine.0x..d4 INFO ROLLBACK
> ---------------------------------------------------------------------------
>
> _SQLError: (ProgrammingError) ERROR: subquery in FROM must have an alias
> HINT: For example, FROM (SELECT ...) [AS] foo.
> _
> SELECT count(id) AS tbl_row_count
> FROM (SELECT azienda.id AS id
> FROM azienda) 'SELECT count(id) AS tbl_row_count \nFROM (SELECT
> azienda.id AS id \nFROM azienda)' {}
>
>
>
> When i use count() function on a mapper - SelectResult , this return
> exactly rowcount, but the same on a select seems to go in error.
>
>
> for Marco Mariani:
>
>>Credo che sia
>>select([ sa.func.count(tbl['azienda'].c.id ])
>>almeno io, con la max(), faccio cosi'..
>
>
> I cannot redefine select_clause because this is a feature for
> returning paginate result and rowcount from the same funtion.
> Example.
>
> i intend
>
> Azienda.my_generic_search( bla, bla, limit, offset
> ).execute().fetchall() --> give paginated result
> Azienda.my_generic_search( bla, bla,
> ).execute().fetchone() --> give rowcount
For the second line, I suppose you want to say...
Azienda.my_generic_search( bla, bla).count().execute().fetchone() -->
give rowcount
>
>
>
>
> Thank you
> Glauco
>
>
>
>
>
>
>
>
>
>--
>+------------------------------------------------------------+
> Glauco Uri - Programmatore
> glauco(at)allevatori.com
>
> Sfera Carta Software® [EMAIL PROTECTED]
> Via Bazzanese,69 Casalecchio di Reno(BO) - Tel. 051591054
>+------------------------------------------------------------+
>
>
>
>
> >
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