>________________________________________ >Von: [email protected] [[email protected]]" im >Auftrag von "Venky >Kandaswamy [[email protected]] > >You can use Postgres WINDOW functions for this in several different ways. For >example, one way of doing it: > >select stts_id, last_value(stts_offset) over (partition by stts_id order by >stts_offset desc) > + last_value(stts_duration) over (partition by stts_id order > by stts_offset desc) >from table >group by stts_id;
another simple solution with distinct on: select distinct on (stts_id, stts_offset) stts_id, stts_offset+stts_duration from table order by stts_id, stts_offset desc Marc Mamin ________________________________________ From: [email protected] <[email protected]> on behalf of Gary Stainburn <[email protected]> Sent: Thursday, July 25, 2013 10:57 AM To: [email protected] Subject: Re: [SQL] value from max row in group by As usual, once I've asked the question, I find the answer myself. However, it *feels* like there should be a more efficient way. Can anyone comment or suggest a better method? timetable=> select stts_id, stts_offset+stts_duration as total_duration timetable-> from standard_trip_sections timetable-> where (stts_id, stts_offset) in timetable-> (select stts_id, max(stts_offset) from standard_trip_sections group by stts_id); stts_id | total_duration ---------+---------------- 1 | 01:35:00 2 | 01:35:00 3 | 01:08:00 4 | 01:38:00 5 | 01:03:00 6 | 01:06:00 (6 rows) timetable=> -- Sent via pgsql-sql mailing list ([email protected]) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-sql -- Sent via pgsql-sql mailing list ([email protected]) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-sql -- Sent via pgsql-sql mailing list ([email protected]) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-sql
