Responded too quickly :-)
If you're already getting a list of the top 100 products (and
displaying them, I assume, in a loop,) then totalling up the prices in
Python really won't hurt at all. I'd only suggest going with my
*previous* suggestion if you *weren't* already fetching the top 100
products.
-Jeff
On Mar 3, 11:34 am, Jeff FW <jeff...@gmail.com> wrote:
> The behavior is there because you can't limit an aggregate function in
> (AFAIK) SQL in that way. It just doesn't make sense--what would this
> actually mean?
>
> select sum(price) from product limit 100;
>
> Really, you'd be limiting the number of *rows* of sum returned, which,
> unless you're using GROUP, is going to be 1. To do what you want,
> you'd need a subselect, which (correct me if I'm wrong,) you'd have to
> manually write in SQL. Like so:
>
> select sum(price) from (select price from product order by price desc
> limit 100) as q;
>
> (That's postgres; your DB may vary.)
>
> I could be completely off-base here, as I haven't delved very far into
> the aggregate code, but from what I can tell, this is the case.
>
> -Jeff
>
> On Mar 3, 11:08 am, Alex Gaynor <alex.gay...@gmail.com> wrote:
>
> > On Tue, Mar 3, 2009 at 8:55 AM, Ross <real...@gmail.com> wrote:
>
> > > I have started using aggregation, but it seems to ignore any slicing I
> > > do on a QuerySet before calling aggregate. This is what I'm doing:
>
> > > Product.objects.order_by("-price")[:100].values("price").aggregate(Max
> > > ("price"), Min("price"))
>
> > > I want the maximum and minimum price for the products with the top 100
> > > largest prices. The aggregate function, however, returns the maximum
> > > and minimum price for all Products--it ignores the [:100] slice.
>
> > > Is this an improper use of aggregation, or am I doing something wrong
> > > with my query?
>
> > Before an aggregation is preformed all limits are removed, so you are seeing
> > expected behavior. I can't remember why this behavior exists though :/
>
> > Alex
>
> > --
> > "I disapprove of what you say, but I will defend to the death your right to
> > say it." --Voltaire
> > "The people's good is the highest law."--Cicero
>
>
--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"Django users" group.
To post to this group, send email to django-users@googlegroups.com
To unsubscribe from this group, send email to
django-users+unsubscr...@googlegroups.com
For more options, visit this group at
http://groups.google.com/group/django-users?hl=en
-~----------~----~----~----~------~----~------~--~---
