zxo102 ouyang <zxo...@gmail.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 -- Really, I'm not out to destroy Microsoft. That will just be a completely unintentional side effect. (Linus Torvalds) "If I was god, I would recompile penguin with --enable-fly." (unknown) Kaufbach, Saxony, Germany, Europe. N 51.05082°, E 13.56889° -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
