Re: Existential quantifier

On Sat, 10 Oct 2009, [utf-8] Dag-Erling Smrgrav wrote:

> Consider the attached schema (filmstars.sql), which is a poorly designed
> database of films and actors. The following query gives me a list of
> films in which either Charlie or Martin Sheen starred:
>
> select fs.film.title, fs.film.year
> from fs.film left join fs.star on fs.film.id = fs.star.film
> where fs.star.last = 'Sheen'
> group by fs.film.title, fs.film.year;
>
> Is there a way to do this without the "group by" clause?

Not at all tested as I don't have access to my db right now, but I think
something like one of these would work:

select fs.film.title, fs.film.year
from fs.film
where exists(select 1 from fs.star where fs.film.id = fs.star.film
and fs.star.last = 'Sheen');

select fs.film.title, fs.film.year
from fs.film
where fs.film.id in (select fs.star.film where fs.star.last = 'Sheen');