Re: Foreign superkey support

From: Erwin <e.smout_at_myonline.be>
Date: 9 Aug 2006 02:29:47 -0700
Message-ID: <1155115787.279257.222480@h48g2000cwc.googlegroups.com>

> I have read various classification systems for constraints, and they
> all seem unnecessary to me. [...] For any
> constraint, we have a set of relations that it is quantified over.

I do think type constraints are different.

I also think that what I call "Tuple constraints" are interesting to be considered separately, I mean expressions that are well-defined "over" one single tuple, i.e. the only "parameters" in the expression are references to attributes of that tuple. From a certain perspective, they might even be regarded as type constraints for some given tuple type (and thus be "different" in the same sense as type constraints for scalar types are "different").

All the others, I think, are indeed basically just database constraints. Received on Wed Aug 09 2006 - 04:29:47 CDT