Re: VIEWs with aggregate functions
От | Paul Makepeace |
---|---|
Тема | Re: VIEWs with aggregate functions |
Дата | |
Msg-id | 20041019121227.GB22444@mythix.realprogrammers.com обсуждение исходный текст |
Ответ на | Re: VIEWs with aggregate functions (Tom Lane <tgl@sss.pgh.pa.us>) |
Список | pgsql-novice |
Je 2004-10-14 05:09:16 +0100, Tom Lane skribis: > Paul Makepeace <postgresql.org@paulm.com> writes: > > CREATE VIEW weekly_bar_info AS > > SELECT bar_name, > > MIN(bar_date) AS earliest_date, MAX(bar_date) AS latest_date, > > MIN(bar) as min_bar, MAX(bar) as max_bar > > FROM bar_data > > WHERE valid_weekly='t' > > GROUP BY bar_name > > > What I'd like to be able do is WHERE bar_name = ? AND bar_date >= ? > > i.e. select over a date range but that isn't directly possible with the > > VIEW as is. > > You can certainly select on bar_name, but you can't select on bar_date > because the view doesn't expose bar_date, only some statistics about > it. I suppose that you want the WHERE clause to filter the bar_data > rows before the aggregation happens (is that correct??) and you just > can't do that with a view. Yes, that's right, that is indeed what I was after. > If it worked like that then the WHERE clause > would not simply limit the set of rows returned by the view but actually > change some of the values in those rows, and that's totally contrary to > the SQL worldview. > > I think you're stuck with writing it out as one big query :-( OK thanks for the confirmation - I suspected that was the case but wanted to be sure! Cheers, Paul > regards, tom lane -- Paul Makepeace .............................. http://paulm.com/inchoate/ "What is the origin of happiness? Badly spelt." -- http://paulm.com/toys/surrealism/
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