On Tue, Feb 17, 2009 at 5:54 PM, Malcolm Tredinnick
<[email protected]> wrote:
>
> Hi Ian,
>
> On Tue, 2009-02-17 at 16:05 -0700, Ian Kelly wrote:
> [...]
>> The solution that I'm proposing is to use the extra select expression
>> itself in the group by, rather than the alias. This passes the tests
>> across all four included backends, and seems to work in general as
>> long as the expression is not a scalar subquery (in which case I think
>> a general solution would require advanced inspection of the
>> expression). But it bothers me a bit because it just feels fragile.
>
> I'm pretty tired today and under a pile of past-urgent things to do, so
> excuse the request for training wheels on this one... can you give a
> short SQL example of what you're talking about here (before vs. after).
No problem. Take the queryset
`Author.objects.extra(select={'sqrt_age':
'sqrt(age)'}).values('sqrt_age').annotate(Count('book'))`
Current SQL: SELECT (sqrt(age)) AS "SQRT_AGE",
COUNT("AGGREGATION_REGRESS_BOOK_AC81D"."BOOK_ID") AS "BOOK__COUNT"
FROM "AGGREGATION_REGRESS_AUTHOR" LEFT OUTER JOIN
"AGGREGATION_REGRESS_BOOK_AC81D" ON ("AGGREGATION_REGRESS_AUTHOR"."ID"
= "AGGREGATION_REGRESS_BOOK_AC81D"."AUTHOR_ID") GROUP BY "SQRT_AGE"
Proposed SQL: SELECT (sqrt(age)) AS "SQRT_AGE",
COUNT("AGGREGATION_REGRESS_BOOK_AC81D"."BOOK_ID") AS "BOOK__COUNT"
FROM "AGGREGATION_REGRESS_AUTHOR" LEFT OUTER JOIN
"AGGREGATION_REGRESS_BOOK_AC81D" ON ("AGGREGATION_REGRESS_AUTHOR"."ID"
= "AGGREGATION_REGRESS_BOOK_AC81D"."AUTHOR_ID") GROUP BY (sqrt(age))
Regards,
Ian
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