Re: Order By for aggregate functions (Simulating Group_concat)

On Thu, Sep 01, 2005 at 05:14:41PM +0200, Martijn van Oosterhout wrote:
> On Thu, Sep 01, 2005 at 10:04:12AM +0100, Charlotte Pollock wrote:
> > What I want to be able to do is pass and order by field to the aggregate so
> > I can be certain I get the list of strings in the correct order.
>
> Order them before the aggregate?
>
> SELECT aggregate(field) FROM (SELECT field FROM xxx ORDER BY wherever) x;

I've occasionally relied on this but I've never been completely
comfortable with it.  Is there any guarantee that the subquery's
ordering will be maintained as rows are fed to the aggregate, or
is that just an accident of the current implementation?

--
Michael Fuhr