Dino Vliet wrote on 16.05.2010 18:07:
Dear postgresql experts,
I want to know if postgresql has facilities for getting the first and or
the last in a by group.
Suppose I have the following table:
resnr,dep,arr,cls,dbd meaning reservationsnumber, departure station,
arrival station, the class of the reservation and the
daysbeforedeparture and records like:
xxx,NYC,BRA,C,80
xxx,NYC,BRA,M,75
xxx,NYC,BRA,Q,50
yyy,WAS,LIS,T,55
zzz,NYC,LIS,Z,40
zzz,NYC,LIS,J,39
I want to select only the most recent records being:
xxx,NYC,BRA,Q,50
yyy,WAS,LIS,T,55
zzz,NYC,LIS,J,39
Something like this?
SELECT *
FROM your_table t1
WHERE dbd = (SELECT min(dbd)
FROM your_table t2
WHERE t2.dep = t1.dep
AND t2.arr = t1.arr
AND t2.resnr = t1.resnr)
Regards
Thomas
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