Re: [SQL] Finding the "most recent" rows
От | Chris Bitmead |
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Тема | Re: [SQL] Finding the "most recent" rows |
Дата | |
Msg-id | 37286C86.8E0472A6@bigfoot.com обсуждение исходный текст |
Ответ на | Re: [SQL] Finding the "most recent" rows (Brook Milligan <brook@trillium.NMSU.Edu>) |
Ответы |
Re: [SQL] Finding the "most recent" rows
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Список | pgsql-sql |
Herouth Maoz wrote: > Tables are considered as unordered sets. There can not be anything in the > standard that relies on the order in the table. And what do you mean by > inserting a preceding ORDER BY step? He was suggesting that an ORDER BY combined with a DISTINCT might be a good way of solving the difficult problem of finding the, say, max(field) in different groups in the table. (And it does work for postgresql) Like a SELECT ...GROUP BY except getting back not just the group fields but all fields. You say that a table is "considered an unordered set". But surely a table is not an unordered set if you've specified an ORDER BY clause? This idea is so nice, it would be ashame to dismiss it too quickly. -- Chris Bitmead http://www.bigfoot.com/~chris.bitmead mailto:chris.bitmead@bigfoot.com
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