INSERT ... SELECT statement

[Stefano Giorgetti]

I need to execute an INSERT...SELECT query.
INSERT HIGH_PRIORITY INTO stations_data
   (station_id,
   Tmin,
   Tmax,
   Tmed,
   RHmin,
   RHmax,
   RHmed,
   rain,
   Wmax,
   slpres,
   insertion_date)
(
   SELECT
       stations.station_id AS stId,
       min(stations_rt_data.T) AS tmax,
       max(stations_rt_data.T) AS tmin,
       avg(stations_rt_data.T) AS tmed,
       min(stations_rt_data.RH) AS rhmin,
       max(stations_rt_data.RH) AS thmax,
       avg(stations_rt_data.RH) AS rhmed,
       sum(stations_rt_data.rain) AS rain,
       max(stations_rt_data.Wmax) AS wmax,
       stations_rt_data.pres AS pres,
       NOW() AS tempo
   FROM (
       stations INNER JOIN stations_rt_data ON stations.code = 
stations_rt_data.station_id
       )
   WHERE
       stations_rt_data.observation_datetime_gmt
       BETWEEN DATE_FORMAT('2005/01/21 > 00:00:00', '%Y%m%d%H%i%s')
       AND DATE_FORMAT('2005/01/21 > 23:59:59', '%Y%m%d%H%i%s')
   GROUP BY
       stations_rt_data.station_id
)

It works fine for every value bt *stations_rt_data.pres*:it looks for 
all observations collected during the past 24 hours.
But I need to get the value of this field at a particular 
*stations_rt_data.observation_datetime_gmt

*Can I modify this query in order to get *stations_rt_data.pres* select 
for a particular *stations_rt_data.observation_datetime_gmt *leaving 
other fields selected as shown in the query WHERE part?

Thanks!
*
*