| From: | Chris Bitmead <chris(dot)bitmead(at)bigfoot(dot)com> |
|---|---|
| To: | pgsql-sql(at)postgreSQL(dot)org |
| Subject: | Re: [SQL] Finding the "most recent" rows |
| Date: | 1999-04-29 14:28:22 |
| Message-ID: | 37286C86.8E0472A6@bigfoot.com |
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| Lists: | 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(dot)bitmead(at)bigfoot(dot)com
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