SQL Help...

Hi,

I'm trying to get a few constraint checks on a table but I'm not sure how to implement it. Heres what its supposed to do:

I have a table Connection with attributes ipA portA ipB portB. A particular connection is two way, but I don't want to add a connetion twice, since it would be redundant. The connection on a particular ip/port can only happen once though (obviously).

So, to make sure that this condition is held I need to check that ipA portA among all values in those 2 columns are unique (which can be done just with a unique constraint) but, I also need to check that the ip and port is not in ipB portB either..

Could anyone give me a hand? I don't know how to implement this. Could it be done with a check constraint in the table creation?

Thanks.

Darren