Re: Foreign superkey support

> 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").

I overlooked the fact that two distinct relvars can be of the same relation type (and thus contain tuples of the same tuple type), but the constraints on the tuples might be different anyway. Thus "tuple constraints" are relvar-dependent after all, and thus just database constraints.

Sorry. Received on Wed Aug 09 2006 - 14:57:34 CEST