From: | Andreas Kretschmer <akretschmer(at)spamfence(dot)net> |
---|---|
To: | pgsql-general(at)postgresql(dot)org |
Subject: | Re: An issue with max() and order by ... limit 1 in postgresql8.3-beta3 |
Date: | 2010-01-09 18:04:18 |
Message-ID: | 20100109180418.GA30528@tux |
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Lists: | pgsql-general |
zxo102 ouyang <zxo102(at)gmail(dot)com> wrote:
> Hi everyone,
> I am using postgresql 8.3-beta3. I have a table 'test' with three fields:
I'm guessing you mean 8.4-beta3, right?
> Any suggestions for the best way to get maximum data value and corresponding
> "time" for each group of sid in my case?
Based on your data:
test=*# select * from test;
sid | data | date
-----+------+---------------------
1 | 1.1 | 2009-09-01 01:00:00
1 | 2.1 | 2010-01-01 01:00:20
2 | 3.1 | 2009-09-01 01:00:10
2 | 0.1 | 2010-01-01 01:00:30
(4 Zeilen)
Try:
Zeit: 0,227 ms
test=*# select distinct on (sid) sid, data, date from test order by sid, data desc, date;
sid | data | date
-----+------+---------------------
1 | 2.1 | 2010-01-01 01:00:20
2 | 3.1 | 2009-09-01 01:00:10
(2 Zeilen)
Andreas
--
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unintentional side effect. (Linus Torvalds)
"If I was god, I would recompile penguin with --enable-fly." (unknown)
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Previous Message | Tom Lane | 2010-01-09 17:19:52 | Re: Table appears on listing but can't drop it |