Re:Pipe Syntax in SQL
by andy800 on Saturday August 24, 2024 @02:20PM
(#41340213)
If you perform an aggregation query in a CTE, then filter on that in a subsequent query, that is different, because you have also added another SELECT and FROM. You would use WHERE in that case whether using a CTE or just an outer query on an inner subquery. HAVING is different from WHERE because it filters after the aggregation, without requiring a separate query with an extra SELECT.
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Re:Pipe Syntax in SQL
by RaftPeople on Saturday August 24, 2024 @05:21PM
(#41341620)
> HAVING is different from WHERE because it filters after the aggregation, without requiring a separate query with an extra SELECT.
Personally I rarely use HAVING and instead use WHERE with subqueries for the following reasons:
1-I don't like repeating/duplicating a bunch of complex calcs, easier to just do WHERE in outer query on result
2-I typically have outer queries anyway for multiple reasons: break logic into reasonable chunks for humans, also for join+performance reasons (to give the optimizer a better chance at not getting confused)