Re: question about a select

On Thu, 9 Oct 2003, Cindy wrote:

> Stephan Szabo writes:
> >On Thu, 9 Oct 2003, Cindy wrote:
> >> Text=# select distinct on (y_level) y_level, byteloc from
> >> citations_by_level where aid=543 and wid=1 order by byteloc;
> >> ERROR: SELECT DISTINCT ON expressions must match initial ORDER BY
> >> expressions
> >
> >Maybe something like:
> >
> >select y_level from (select distinct on (y_level) y_level,
> >byteloc from citations_by_level where aid=543 and wid=1) tab order by
> >byteloc;
>
> Hm...this seems to pick out the y_level with the largest byteloc
> associated with it...I need the y_level with the smallest byteloc and
> then sorted by that...lemme play this, but any other suggestions also
> welcomed...

I think an order by y_level, byteloc in the subquery might give you the
ordering you want for the distinct on step, and then the outer order by
will order the y_levels by their respective bytelocs.