Re: atomic
From: Bob Badour <bbadour_at_pei.sympatico.ca>
Date: Fri, 02 Nov 2007 12:48:23 -0300
Message-ID: <472b46cb$0$14877$9a566e8b_at_news.aliant.net>
>
> Sorry, let me take that first sentence back as I didn't notice at first
> that you are called <order> a count. So I guess I should say the
> predicate I had in mind was "the pizza for order <order> has the set of
> toppings <toppings>.
>
> I still wonder why one would want both tuples to apply to the same pizza.
Date: Fri, 02 Nov 2007 12:48:23 -0300
Message-ID: <472b46cb$0$14877$9a566e8b_at_news.aliant.net>
paul c wrote:
>> Roy Hann wrote: >> >>> "paul c" <toledobythesea_at_ooyah.ac> wrote in message >>> news:08HWi.167005$Da.137917_at_pd7urf1no... >>> >>>> If I may dodge the ordering question for now and continue with my >>>> casual graphics, how could a relation like the following be useful? >>>> (assuming one pizza per order and ignoring pizza size) >>>> >>>> PizzasOrdered: >>>> >>>> Order {Toppings} >>>> _____ __________ >>>> >>>> 1 {Tomato, Sausage, Cheese} >>>> 1 {} >>> >>> >>> If the predicate is something like "The kitchen is currently cooking >>> <order> pizzas with <toppings>", where <order> is a count. (i.e. >>> someone has ordered just a crust--my son would, and someone else has >>> ordered a proper pizza.) I could no doubt invent other possible >>> interpretations. My question is, what predicate did you intend me to >>> use when answering your question? >> >> I think your predicate is fine. ...
>
> Sorry, let me take that first sentence back as I didn't notice at first
> that you are called <order> a count. So I guess I should say the
> predicate I had in mind was "the pizza for order <order> has the set of
> toppings <toppings>.
>
> I still wonder why one would want both tuples to apply to the same pizza.
With your predicate, I doubt one would, which is why one would declare a candidate key that would reject the relation. Received on Fri Nov 02 2007 - 16:48:23 CET