Re: Searching for results with an unknown amount of data - Mailing list pgsql-sql

> > Now, I want to find all objects that have at most properties 1,2,3, say 
>(so
> > something with (1,2) is okay, as is (1,2,3)). I can't see a way to do 
>this
> > -- can anyone help?
>
>It sounds like you are trying to find all objects that do not have any
>properties outside of a specific list. One way to get that list is:

That's exactly right.

>
>SELECT a_id
>   FROM a
>     WHERE
>       NOT EXISTS
>         (SELECT 1
>           FROM b
>           WHERE
>             b.a_id = a.a_id
>             AND
>             b.property NOT IN (1, 2, 3)
>         )
>;

Yupp, this appears to do it! The 'double negation' is very clever.

Thanks a lot,
DL