Help with select with max and min please

  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()

The data in the table is like this:

select hora,remota_id,caudal from historicos;

         hora         | remota_id |  caudal
---------------------+-----------+----------
  2010-05-21 20:00:06 | 04        | 1201.309
  2010-05-21 20:15:08 | 04        | 1201.309
  2010-05-21 20:30:06 | 04        | 1219.803
  2010-05-21 20:45:06 | 04        | 1225.098
  2010-05-21 21:00:06 | 04        | 1238.359
  2010-05-21 21:15:06 | 04        | 1241.015
  2010-05-21 21:30:06 | 04        | 1241.015
  2010-05-21 21:45:06 | 04        |  1246.33
  2010-05-21 22:00:06 | 04        | 1248.989
  2010-05-21 22:15:06 | 04        | 1235.704
  2010-05-21 22:30:06 | 04        |  1222.45
  2010-05-21 22:45:06 | 04        | 1201.309
  2010-05-21 23:00:06 | 04        | 1203.947
  2010-05-21 23:15:06 | 04        | 1219.803
  2010-05-21 23:30:06 | 04        | 1275.649
  2010-05-21 23:45:06 | 04        | 1280.995
  2010-05-22 00:00:06 | 04        |  1294.38
  2010-05-22 00:15:06 | 04        | 1299.742
  2010-05-22 00:30:06 | 04        |  1294.38
  2010-05-22 00:45:06 | 04        |  1294.38
  2010-05-22 01:00:06 | 04        | 1299.742

Can anyone help me?

Best,


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