thanks.
this is good enough, although in general having to fall back to sql is
not portable between different database engines.
i think that at least having methods that return the names of the
underlying database tables and/or fields would be helpful. so that i
could use them in stead of 'myapp_a_bs' or 'a_id'. just in case the
naming scheme changes later. i realise of course that i could go the
other way and make the models use my own names when creating the
tables/fields in the first place.
i appreciate your help
konstantin
On Feb 18, 3:31 pm, "Honza Král" <[EMAIL PROTECTED]> wrote:
> Hi,
> I believe you could use
>
> queryset.extra( select={ 'B_count' : 'SELECT COUNT(*) FROM myapp_a_bs
> WHERE a_id = myapp_a.id' } )
>
> it will result in a slightly different, but equivalent, query:
> SELECT
> myapp_a.id,
> myapp_a,
> ...,
> ( SELECT COUNT(*) FROM myapp_a_bs WHERE a_id = myapp_a.id ) AS "B_count"
> FROM
> ...
>
> or you could call
>
> .b_set.count() on every a object you would get (one query for every
> instance !! )
>
> there is no clean (without SQL) way to do aggregations in django ORM.
>
> On 2/18/07, akonsu <[EMAIL PROTECTED]> wrote:
>
>
>
>
>
>
>
> > hello,
>
> > class A(models.Model):
> > ....
> > bs = models.ManyToManyField('B')
>
> > class B(models.Model):
> > ....
>
> > how to implement this query:
>
> > select *
> > from myapp_a
> > inner join (select a_id, count(*)
> > from myapp_a_bs
> > group by a_id) as a
> > on myapp_a.id=a.a_id;
>
> > thanks for any help!
> > konstantin
>
> --
> Honza Kr?l
> E-Mail: [EMAIL PROTECTED]
> ICQ#: 107471613
> Phone: +420 606 678585- Hide quoted text -
>
> - Show quoted text -
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