Re: GROUP BY, ORDER & LIMIT ?

select class, size from X t1 where size in (select size from X t2
where t2.class=t1.class order by size desc limit 5);

On Tue, May 6, 2008 at 1:22 PM, Kynn Jones <kynnjo(at)gmail(dot)com> wrote:

> Suppose table X has two columns: class (TEXT) and size (INT). I want a
> listing showing the (up to) 5 largest values of "size" for each value of
> "class" (for some values of "class" the total number of available records
> may be less than 5).
>
> What would be the simplest way to achieve such a listing? It seems like
> something one could do with GROUP BY, ORDER, and LIMIT, but I can't figure
> out the right syntax for this query.

Warning, this is typed directly into mail:
select class, size from X t1 where size in (select size from X t2
where t2.class=t1.class order by size desc limit 5);

That should do the trick. The only problem is if you've got duplicated
size values, you could end up with more than 5 per class.

--
- David T. Wilson
david(dot)t(dot)wilson(at)gmail(dot)com