Re: Find min and max values across two columns?
От | Amos Hayes |
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Тема | Re: Find min and max values across two columns? |
Дата | |
Msg-id | 0C305AAF-7DA6-40BF-B118-2E63C2A27748@polkaroo.net обсуждение исходный текст |
Ответ на | Re: Find min and max values across two columns? (Rod Taylor <pg@rbt.ca>) |
Список | pgsql-sql |
Your tips were great and I have hunted down the relevant pages in the docs. Thanks guys! -- Amos On 24-Mar-06, at 4:20 PM, Rod Taylor wrote: > On Fri, 2006-03-24 at 16:20 -0500, Tom Lane wrote: >> Rod Taylor <pg@rbt.ca> writes: >>> The reason for the subselect is to prevent multiple calculations of >>> individual column aggregates. I believe it *may* be calculated >>> multiple >>> times otherwise this would work just as well: >> >>> select case when max(a) > max(b) then max(a) else max(b) end as >>> max from >>> tab; >> >> Just for the record, we've gotten that right since 7.4. greatest() >> would be a notationally cleaner solution than CASE, but multiple >> occurrences of identical aggregates don't cost much of anything. > > Thanks. I could not remember one way or the other. > > -- > > > ---------------------------(end of > broadcast)--------------------------- > TIP 1: if posting/reading through Usenet, please send an appropriate > subscribe-nomail command to majordomo@postgresql.org so that > your > message can get through to the mailing list cleanly
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