| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | "Richard Broersma" <richard(dot)broersma(at)gmail(dot)com> |
| Cc: | "Ruben Gouveia" <rubes7202(at)gmail(dot)com>, pgsql-sql <pgsql-sql(at)postgresql(dot)org> |
| Subject: | Re: Aggregates in WHERE clause? |
| Date: | 2008-09-11 12:03:23 |
| Message-ID: | 16867.1221134603@sss.pgh.pa.us |
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| Lists: | pgsql-sql |
"Richard Broersma" <richard(dot)broersma(at)gmail(dot)com> writes:
> On Wed, Sep 10, 2008 at 4:11 PM, Ruben Gouveia <rubes7202(at)gmail(dot)com> wrote:
>> ERROR: aggregates not allowed in WHERE clause
> Having clause works on agregates. If you want to force it in the
> where, you need to put the groupby in a sub-query.
The way I like to think about it is "WHERE filters rows before aggregate
functions are computed; HAVING filters them afterwards". Seen in those
terms, it's obvious why WHERE can't contain any aggregates.
regards, tom lane
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