Joseph,
> playpen=# select a, sum(b) as dsum from taba where dsum > 5 group
> by(a);
> ERROR: Attribute 'dsum' not found
>
> Why can we GROUP BY on an alias but not do a WHERE on an alias? I
> have a subselect that
> explain shows is being run twice if I have to put it in the WHERE
> clause.
Ah, but you are not trying to do a WHERE on an alias ... you are trying
to do a WHERE on an *aggregate*, which is a different thing. Consult
your favorite SQL manual; the construction you want is:
SELECT a, sum(b) as dsum
FROM taba
GROUP BY a
HAVING dsum > 5;
-Josh Berkus
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