Re: [SQL] value from max row in group by
Sorry, but I never thought. I'm developing this on my server I'm developing it for someone else who wants it in a WordPress / MySQL environment (I don't know MySQL). Would this or something similar work in mysql? (Sorry for going O.T.) On Thursday 25 July 2013 19:53:06 Marc Mamin wrote: Von: pgsql-sql-ow...@postgresql.org [pgsql-sql-ow...@postgresql.org]quot; im Auftrag von quot;Venky Kandaswamy [ve...@adchemy.com] 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 -- Gary Stainburn Group I.T. Manager Ringways Garages http://www.ringways.co.uk -- Sent via pgsql-sql mailing list (pgsql-sql@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-sql
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 (pgsql-sql@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-sql
Re: [SQL] value from max row in group by
On Thu, Jul 25, 2013 at 10:45 AM, Gary Stainburn gary.stainb...@ringways.co.uk wrote: Hi folks, I need help please. I have a table of trip section details which includes a trip ID, start time as an offset, and a duration for that section. I need to extract the full trip duration by adding the highest offset to it's duration. I can't simply use sum() on the duation as that would not include standing time. Using the data below I would like to get: 1 | 01:35:00 2 | 01:35:00 3 | 01:06:00 4 | 01:38:00 5 | 01:03:00 6 | 01:06:00 How about using a WINDOW function? Eg. select stts_id, total from (select stts_id, stts_offset+stts_duration as total, row_number() over (partition by stts_id order by stts_offset desc) as rank from sts) s where rank = 1 order by stts_id;
Re: [SQL] value from max row in group by
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-ow...@postgresql.org pgsql-sql-ow...@postgresql.org on behalf of Gary Stainburn gary.stainb...@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= -- Sent via pgsql-sql mailing list (pgsql-sql@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-sql -- Sent via pgsql-sql mailing list (pgsql-sql@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-sql
Re: [SQL] value from max row in group by
Von: pgsql-sql-ow...@postgresql.org [pgsql-sql-ow...@postgresql.org]quot; im Auftrag von quot;Venky Kandaswamy [ve...@adchemy.com] 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: pgsql-sql-ow...@postgresql.org pgsql-sql-ow...@postgresql.org on behalf of Gary Stainburn gary.stainb...@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= -- Sent via pgsql-sql mailing list (pgsql-sql@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-sql -- Sent via pgsql-sql mailing list (pgsql-sql@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-sql -- Sent via pgsql-sql mailing list (pgsql-sql@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-sql
