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Beginner Question...

From: James David Smith <james(dot)david(dot)smith(at)gmail(dot)com>
To: pgsql-novice(at)postgresql(dot)org
Subject: Beginner Question...
Date: 2011-07-09 16:41:36
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-novice
Hi everyone,

Could someone help me with this question please? I have a table with
four columns:

- gps_id (primary key)
- date_time
- crimes_link (foreign key)
- osgb36_geom

The data in the table involves lots of gps tracks of different
journeys. They are grouped into journeys by the 'crimes_link' field.
So for example the first 50 rows have an identical 'crimes_link'
field, then the next 50 rows a different value in 'crimes_link', then
the next 50 rows a different one, etc. What I would like to do is to
select the beginning location of each journey. This query gives me the
date_time of the beginning of the journey:

SELECT crimes_link, MIN(date_time)
FROM camdengps3
GROUP BY crimes_link;

However I need to add the osgb36_geom column into the query and am unable too.

Any ideas how to do this please?

Thank you

James Smith


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