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
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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