Thanks to Rhino & Dan for the corrections, HAVING in that query
makes it return only id values for which there is one row, and the
header is wrong since "first row of every group" doesn't mean anything
without explicit ordering.
PB
-----
Dan Bolser wrote:
On Mon, 11 Apr 2005, Rhino wrote:
----- Original Message -----
From: "Dan Bolser" <[EMAIL PROTECTED]>
To: <mysql@lists.mysql.com>
Sent: Monday, April 11, 2005 5:58 AM
Subject: Display 1st row of every group?
I read with great interest this
http://www.artfulsoftware.com/queries.php#4
Display 1st row of every group
SELECT id
FROM tbl
GROUP BY id
HAVING count(*) = 1;
Despite what the heading says for that query, it is NOT going to return the
first row of every group. In fact, it is going to return only groups that
contain one row. For example, given this data:
ID
--
5
5
5
6
7
7
8
8
8
9
That query will return return this:
id
--
6
9
In other words, it is returning only groups where there is a single ID with
that value. Note also that it is returning ONLY an ID, not the ID plus the
rest of the row. Their description of what the query does is just plain
wrong.
Delicious second opinion!
Thanks for the reply - if you see my second post you see I fixed my
problem.
Cheers,
Dan.
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