From: terry@greatgulfhomes.com
To: "Postgres (E-mail)" <pgsql-docs@postgresql.org>
Subject: DISTINCT and ORDER BY issue
Date: Thu, 23 May 2002 10:49:07 -0400
Message-ID: <001401c20268$fdff0c40$2766f30a@development.greatgulfhomes.com>
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Importance: Normal

I know what I am doing wrong:  The order by needs to match the DISTINCT
fields.

Here's what I am doing:  Get the 10 most recent applications user has used
to put in their "recently used" menu.

So I need to ORDER BY user_app_access_log.access_stamp DESC

But I want each record distinct, eg if the last 5 hits were all for the same
app, I want 1 record returned for that.  So if I put the access_stamp field
in the DISTINCT field set, then I go back to getting repeats of apps, hence
not 10 unique app names...

I wonder if there is a way to use an aggregate function to just return the
first value, (ignoring the rest of the group), and use the group by clause
on the app_name?

Any ideas is appreciated.

Here is my query/error message:
Error while executing the query; ERROR: For SELECT DISTINCT, ORDER BY
expressions must appear in target list


SELECT DISTINCT applications.app_name, applications.app_long_name,
applications.app_url, user_access.in_new_window
FROM applications, user_access, user_app_use_log
WHERE user_app_use_log.user_id = '1'
AND user_app_use_log.app_name != 'index'
AND user_access.app_name = user_app_use_log.app_name
AND user_access.user_id = user_app_use_log.user_id
AND user_access.division_id = 'GGH'
AND applications.app_name = user_access.app_name
ORDER BY user_app_use_log.access_stamp DESC
LIMIT 10"

Thanks in advance

Terry Fielder
Network Engineer
Great Gulf Homes / Ashton Woods Homes
terry@greatgulfhomes.com