Re: problematic query (for me ;-)

"Kim Petersen"  wrote in message
news:3E660A41.7040509@kyborg.dk...
> I'm trying to get a hint as to how i can solve this problem:
>
> i have a table:
>
>   n | t
> ---+---
>   1 | 2
>   1 | 5
>   2 | 3
>   2 | 5
>   3 | 4
>   3 | 3
> (6 rows)
>
> now i want to find the pairs (n1,n2) where no t's collide - eg in this
> table it would be (1,3) and (3,1).

SELECT DISTINCT nt1.n, nt2.n FROM nt nt1, nt nt2
WHERE NOT EXISTS (   (SELECT t from nt where n=nt1.n) INTERSECT   (SELECT t from nt where n=nt2.n))
n | n
---+---1 | 33 |1
(2 rows)

I'm not sure that it scales well to large datasets...

/Bjarke