Re: foreign key constraint versus referential integrity constraint
From: Bob Badour <bbadour_at_pei.sympatico.ca>
Date: Sun, 25 Oct 2009 11:40:45 -0300
Message-ID: <4ae46371$0$23769$9a566e8b_at_news.aliant.net>
>
> None in theory, I thought you were talking about attributes in the same
> domain.
Date: Sun, 25 Oct 2009 11:40:45 -0300
Message-ID: <4ae46371$0$23769$9a566e8b_at_news.aliant.net>
paul c wrote:
> Bob Badour wrote:
>
>> paul c wrote: >> >>> Bob Badour wrote: >>> ... >>> >>>> You asked about semantic joinability. Semantically, the join works >>>> if like-named attributes have an equality comparison defined and not >>>> if they don't. >>>> ... >>> >>> In RT, how could they not define equality? >> >> What reason would one have to define an equality comparison to compare >> employee ids with department ids or with names? Or charge with current >> or potential? Or age with price?
>
> None in theory, I thought you were talking about attributes in the same
> domain.