Re: A new proof of the superiority of set oriented approaches: numerical/time serie linear interpolation

Brian Selzer wrote:
> Clarification. In a closed world, the assignment itself provides a frame of
> reference for comparison, so it *can* be determined whether or not the
> values are identical, or whether or not one or more corresponding relations
> within each value are identical. As often is the case, I'm wrong: logical
> identity can be used. On the other hand, it can only be determined that a
> tuple in a relation in one value is identical to a tuple in a relation in
> the other. If a relation in the replaced value is neither a superset nor a
> subset of the relation with the same name in the assigned value, and if more
> than one element is different, then a mapping is required for comparison.
> And again, since key updates have been part of the model since its
> inception, and since surrogates aren't, assignment would permit certain
> constraints to be bypassed--a clear violation of one of Codd's rules.

Straw man. If transition constraints were tuple-based, and assignment would allow you to bypass them, then they would be bypassed. But I don't think anyone is advocating that.

-- 
Jon