Subject: GROUP BY [Was: SELECT]

>From: "Ron Piggott (PHP)"
>Reply-To: ron.php@actsministries.org
>To: PHP DB
>Content-Type: text/plain
>Date: Sat, 10 Dec 2005 20:04:28 -0500
>Message-Id: <1134263069.3515.86.camel@localhost.localdomain>
>Mime-Version: 1.0
>Content-Transfer-Encoding: 7bit
>Subject: SELECT
>
>I am trying to put together a SELECT syntax. I am querying a response
>database and I only want to obtain each user's name once even if they
>have given more than 1 response.
>
>$query="SELECT * FROM conversation_table WHERE conversation_reference =
>$conversation_currently_displayed";

.... Add "GROUP BY conversation_user_id" or whatever column you use to
identify the user.

http://dev.mysql.com/doc/refman/5.0/en/select.html

Note that GROUP BY comes *before* any ORDER BY in your select (which
you aren't doing). By default, MySQL will order by the grouped
columns initially. Other databases you'd have to include the GROUP BY
column(s) in the select * statement, but MySQL allows you to do this
with non-selected fields as well.

Then spend some time on the MySQL site looking at the 'aggregate
functions' area now you've grouped the results - you'll find some
useful stuff you can do once that's happened :

http://dev.mysql.com/doc/refman/5.0/en/group-by-functions.ht ml

Cheers - Neil

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