Re: constraints in algebra instead of calculus

"Bob Badour" <bbadour_at_pei.sympatico.ca> wrote in message news:46550391$0$4021$9a566e8b_at_news.aliant.net...
> paul c wrote:
>
>> Brian Selzer wrote:
>>
>>> "paul c" <toledobythesea_at_oohay.ac> wrote in message
>>>
>>>> ...
>>>> If view V = A & B, surely constraint C on the view, giving V & C, would
>>>> be manipulated by an engine with the same effect as the expression (A &
>>>> C) & (B & C).
>>>>
>>>> I've never heard of anybody requiring expressions to result in BCNF
>>>> values, surely that would cripple an algebra.
>>>
>>> They don't. Nor should they. But an expression defining a view can
>>> involve anything, restriction, difference, aggregation, division. How
>>> does a constraint on the view map to constraints on the base tables?
>>
>> I would think restriction and difference can be distributed naively as
>> above. If nobody else here formulates the other two, I'll be getting
>> around to it in the next few months for other reasons.
>
> I don't know why you indulge him. Constraints are simply wffs. One can map
> a view constraint to the base relations by simple substitution.

Why should you care? Why have you made it your mission in life to drive me from this group? Do you perceive me as some sort of threat?

I think that the manipulative comments that you've been dropping are grossly presumptuous, and if I were a recipient of one of them, I might even take offense. You've discovered that direct name-calling, bullying, and outright abuse did not drive me away (I have a pretty thick skin.), so you've altered your tactics and started subtly attacking anyone who responds to my posts. It's not as if they can't think for themselves. If my ideas do not merit consideration, they can choose to ignore them all by themselves. They do not need any prompting from you. They certainly don't deserve to be told that they're stupid for responding. They can respond to whomever they please: they don't have to ask you for permission, nor do they owe you any explanation! Received on Thu May 24 2007 - 07:56:30 CEST