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" <dmb@stripped>
>>To: <mysql@stripped>
>>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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