Goran Hasse <gor...@gmail.com> wrote:
> [...]
> I would like to do;
> freescada=> select * from counter_log_view where name='CNT-3' and timestamp
> < '2010-05-23 18:00:00' order by timestamp desc limit 1;
> name | timestamp | count
> -------+---------------------------+-------
> CNT-3 | 2010-05-23 17:53:18.58674 | 43
> (1 rad)
> freescada=> select * from counter_log_view where name='CNT-3' and timestamp
> < '2010-05-23 19:00:00' order by timestamp desc limit 1;
> name | timestamp | count
> -------+----------------------------+-------
> CNT-3 | 2010-05-23 18:53:19.151988 | 50
> (1 rad)
> freescada=> select * from counter_log_view where name='CNT-3' and timestamp
> < '2010-05-23 20:00:00' order by timestamp desc limit 1;
> name | timestamp | count
> -------+----------------------------+-------
> CNT-3 | 2010-05-23 19:53:19.683514 | 51
> (1 rad)
> In one query. Is this possible in *any* way?
Sure:
| SELECT DISTINCT ON (DATE_TRUNC('hour', timestamp)) name, timestamp, count
| FROM counter_log_view
| ORDER BY DATE_TRUNC('hour', timestamp), timestamp DESC;
Tim
P. S.: Naming columns "timestamp" and "count" will lead to
trouble :-).
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