Re: Select the max on a field

On Thu, 12 Sep 2002, Gaetano Mendola wrote:

> Hi all,
>
> Suppose that I have a table like this:
>
>
> att_1 | att_2 | att_3 | att_4
> --------------------------------
> 1 | a | y | y1
> 2 | b | y | y2
> 3 | a | xx | y3
> 4 | c | zz | y4
> 5 | a | t | y5
> 6 | c | x | y6
>
>
>
> I want obtain all row that have for each att_2
> the max of att_1
>
> some like
>
> SELECT *
> FROM MY_TABLE
> GROUP BY att_2
> HAVING att_1 = max ( id_user_log)

If you don't mind using postgres extensions and
don't need a particular att_1 ordering:

select distinct on (att_2) * from test
order by att_2, att_1 desc;

Otherwise I'm not sure you can do it without
a subselect somewhere.