Re: foreign key constraint versus referential integrity constraint
From: Bob Badour <bbadour_at_pei.sympatico.ca>
Date: Thu, 29 Oct 2009 11:30:50 -0300
Message-ID: <4ae9a71a$0$26500$9a566e8b_at_news.aliant.net>
>
> I usually try to omit at least two out of three of those, otherwise even
> I can't guess what I'm talking about! Being of a minimalist persuasion,
> not wanting more concepts than I can handle, I think I'd rather have
> constraints, unlike CJ Date's, that are applied against values without
> requiring them to be 'truth-valued' and 'and-ed' if you will. I don't
> have a good name for this.
Date: Thu, 29 Oct 2009 11:30:50 -0300
Message-ID: <4ae9a71a$0$26500$9a566e8b_at_news.aliant.net>
paul c wrote:
>> paul c wrote: >> >>> Mr. Scott wrote: >>> ... >>> >>>> Constraints specify what can be true, not what is supposed to be >>>> true. ... >>> >>> I thought constraints constrain, ie., limit. (I've often thought that >>> isn't enough in practice, eg., I've never seen a default defined >>> algebraically and beyond that I wouldn't mind a variation on >>> constraints that lets me force an assertion, eg., some tuple that is >>> always present, whether the user has thought to include it or not, >>> probably CJ Date would disagree with that.) >> >> I cannot make sense of what you wrote. I suspect you have omitted much >> context, internal dialogue and assumptions.
>
> I usually try to omit at least two out of three of those, otherwise even
> I can't guess what I'm talking about! Being of a minimalist persuasion,
> not wanting more concepts than I can handle, I think I'd rather have
> constraints, unlike CJ Date's, that are applied against values without
> requiring them to be 'truth-valued' and 'and-ed' if you will. I don't
> have a good name for this.
If not truth-valued, what would they be? Either something passes the constraint or it doesn't. Received on Thu Oct 29 2009 - 15:30:50 CET