Re: 7.3 "group by" issue

On 21 Feb 2003 at 13:30, Chad Thompson wrote:

> The same applies to group by... Sorry for the confusion.
>
> If the column is not in the select section of the statement, it cant group
> by it.
> Try this.
>
> SELECT element_id as wle_element_id, COUNT(watch_list_id)
> FROM watch_list JOIN watch_list_element
> ON watch_list.id = watch_list_element.watch_list_id
> WHERE
> watch_list.user_id = 1
> GROUP BY wle_element_id

Yes, that works. But so do these.

SELECT watch_list_element.element_id as wle_element_id,
COUNT(watch_list_id)
FROM watch_list JOIN watch_list_element
ON watch_list.id = watch_list_element.watch_list_id
WHERE
watch_list.user_id = 1
GROUP BY watch_list_element.element_id

SELECT element_id as wle_element_id, COUNT(watch_list_id)
FROM watch_list JOIN watch_list_element
ON watch_list.id = watch_list_element.watch_list_id
WHERE
watch_list.user_id = 1
GROUP BY element_id

The original situation which did not work is:

SELECT watch_list_element.element_id as wle_element_id,
COUNT(watch_list_id)
FROM watch_list JOIN watch_list_element
ON watch_list.id = watch_list_element.watch_list_id
WHERE
watch_list.user_id = 1
GROUP BY element_id

My question: why should it not work? It's referring to the same
column as the previous two examples which do work.
--
Dan Langille : http://www.langille.org/