El 08/08/10 21:49, Edoardo Panfili escribió:
On 08/08/10 20.47, Jose Maria Terry wrote:
Hello all,
I need to run a query on a table that holds logged data from several
water flow meters.
I need the first and last values (with their associated time) for every
logger in a time range.
I've tried this that returns the min and max time in the desired range
for every logger, but i don't know how to get the associated data (the
row called caudal) for min and max .
select remota_id,min(hora),max(hora) from historicos where hora >
'2010-08-07' and hora <'2010-08-08 00:03' group by remota_id order by
remota_id;
remota_id | min | max
-----------+---------------------+---------------------
01 | 2010-08-07 00:00:30 | 2010-08-08 00:00:30
02 | 2010-08-07 00:00:06 | 2010-08-08 00:00:06
03 | 2010-08-07 00:00:03 | 2010-08-08 00:00:02
04 | 2010-08-07 00:00:06 | 2010-08-08 00:00:06
05 | 2010-08-07 00:00:01 | 2010-08-08 00:00:02
06 | 2010-08-07 00:00:02 | 2010-08-08 00:00:02
07 | 2010-08-07 00:00:06 | 2010-08-08 00:00:06
09 | 2010-08-07 00:00:06 | 2010-08-08 00:00:06
(8 filas)
I need some like this:
remota_id | min | max | min_caudal | max_caudal
-----------+---------------------+---------------------+------------+------------
01 | 2010-08-07 00:00:30 | 2010-08-08 00:00:30 | 976.04 | 904.21
02 | 2010-08-07 00:00:06 | 2010-08-08 00:00:06 | 829.71 | 764.42
Where min_caudal is the value of caudal in hora = min() and max_caudal
is the same for hora=max()
this can help?
select remota_id,min(hora),max(hora), (SELECT caudal FROM historicos
WHERE remota_id=ooo.remota_id AND hora=min(ooo.hora)) as min_caudal,
(SELECT caudal FROM historicos WHERE remota_id=ooo.remota_id AND
hora=max(ooo.hora)) as max_caudal from historicos AS ooo group by
remota_id order by remota_id;
Edoardo
Thanks, Edoardo!
Works perfect, i've added the date (hora) select and the result is just
what expected:
select remota_id,min(hora),max(hora), (SELECT caudal FROM historicos
WHERE remota_id=ooo.remota_id AND hora=min(ooo.hora)) as min_caudal,
(SELECT caudal FROM historicos WHERE remota_id=ooo.remota_id AND
hora=max(ooo.hora)) as max_caudal from historicos AS ooo where hora >
'2010-08-07' and hora <'2010-08-08 00:03' group by remota_id order by
remota_id;
remota_id | min | max | min_caudal |
max_caudal
-----------+---------------------+---------------------+------------+------------
01 | 2010-08-07 00:00:30 | 2010-08-08 00:00:30 | 2785.727 |
2766.883
02 | 2010-08-07 00:00:06 | 2010-08-08 00:00:06 | 1820.309 |
1860.785
03 | 2010-08-07 00:00:03 | 2010-08-08 00:00:02 | 2296.633 |
2280.154
04 | 2010-08-07 00:00:06 | 2010-08-08 00:00:06 | 1946.548 |
1898.955
05 | 2010-08-07 00:00:01 | 2010-08-08 00:00:02 | 664.5776 |
984.9826
06 | 2010-08-07 00:00:02 | 2010-08-08 00:00:02 | 1103.71
| 1185.17
07 | 2010-08-07 00:00:06 | 2010-08-08 00:00:06 | 452.0654 |
410.4259
09 | 2010-08-07 00:00:06 | 2010-08-08 00:00:06 | 766.8262 |
774.8085
(8 filas)
Best
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