Re: [SQL] DISTINCT ON: speak now or forever hold your peace

On Tue, 25 Jan 2000, Julian Scarfe wrote:

> Tom Lane wrote:
> >
> > If I don't hear loud hollers very soon, I'm going to eliminate the
> > DISTINCT ON "feature" for 7.0. As previously discussed, this feature
> > is not standard SQL and has no clear semantic interpretation.
>
> I use 'distinct on' to get the most recent reports for each of a group of
> locations. E.g.:
>
> create table reports (
> location varchar(16),
> report_time datetime,
> report_text text);
>
> select distinct on location * from reports where location ~~ 'Lond%' order by
> location, reporttime desc;
>
> to get the tuples that offer the most recent reports for each of London,
> Londonderry, Londy etc.
>
> Is there an alternative?

select location, max(report_time) from reports group by location

This also has the negligible advantage that it gives you determinate
results.

--
Peter Eisentraut Sernanders vaeg 10:115
peter_e(at)gmx(dot)net 75262 Uppsala
http://yi.org/peter-e/ Sweden