From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
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To: | Andrew Perrin <andrew_perrin(at)unc(dot)edu> |
Cc: | Marc Sherman <msherman(at)projectile(dot)ca>, pgsql-sql List <pgsql-sql(at)postgresql(dot)org> |
Subject: | Re: Select most recent record? |
Date: | 2001-05-16 14:50:17 |
Message-ID: | 17280.990024617@sss.pgh.pa.us |
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Lists: | pgsql-sql |
Andrew Perrin <andrew_perrin(at)unc(dot)edu> writes:
> Except that he wants max(timestamp) by id; perhaps a GROUP BY would
> help, something like (untested):
Oh, I'm sorry, I missed the "for each id" bit.
> select max(timestamp) from log group by id;
That gives you the max timestamp for each id, all right, but not the
rest of the row in which the max timestamp occurs. I know of no good
way to get that in standard SQL. If you don't mind being nonstandard,
this is exactly the problem SELECT DISTINCT ON is meant for:
select distinct on (id) * from log order by id, timestamp desc;
See the SELECT reference page for more about this.
regards, tom lane
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