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help / color / mirror / Atom feedFrom: Venky Kandaswamy <venky@adchemy.com>
To: Gary Stainburn <gary.stainburn@ringways.co.uk>
To: pgsql-sql@postgresql.org <pgsql-sql@postgresql.org>
Subject: Re: value from max row in group by
Date: Thu, 25 Jul 2013 18:03:58 +0000
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In-Reply-To: <201307251857.10326.gary.stainburn@ringways.co.uk>
References: <201307251845.51079.gary.stainburn@ringways.co.uk>
<201307251857.10326.gary.stainburn@ringways.co.uk>
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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;
________________________________________
Venky Kandaswamy
Principal Engineer, Adchemy Inc.
925-200-7124
________________________________________
From: pgsql-sql-owner@postgresql.org <pgsql-sql-owner@postgresql.org> on behalf of Gary Stainburn <gary.stainburn@ringways.co.uk>
Sent: Thursday, July 25, 2013 10:57 AM
To: pgsql-sql@postgresql.org
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=>
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To: pgsql-sql@postgresql.org
Cc: venky@adchemy.com, gary.stainburn@ringways.co.uk
Subject: Re: value from max row in group by
In-Reply-To: <9d70bbaa0ce84bab8c0467c83fbc01c7@BY2PR05MB237.namprd05.prod.outlook.com>
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