Re: delete cascade
From: Bob Badour <bbadour_at_pei.sympatico.ca>
Date: Wed, 18 Apr 2007 16:45:38 GMT
Message-ID: <SWrVh.25722$PV3.262479_at_ursa-nb00s0.nbnet.nb.ca>
>
> I'm taking "inconsistent update" to mean "an update that would leave the
> database in an inconsistent state".
> Is my reading correct? And, if so, do the two phrases mean the same thing?
Date: Wed, 18 Apr 2007 16:45:38 GMT
Message-ID: <SWrVh.25722$PV3.262479_at_ursa-nb00s0.nbnet.nb.ca>
David Cressey wrote:
> "Bob Badour" <bbadour_at_pei.sympatico.ca> wrote in message
> news:FepVh.25684$PV3.261993_at_ursa-nb00s0.nbnet.nb.ca...
>
>
>>The normal effect of a constraint is simply to block any inconsistent >>update. You gave an english phrase suggesting all foreign keys should >>cascade deletes, and I gave a similar english phrase suggesting they >>should not. Both are useful.
>
> I'm taking "inconsistent update" to mean "an update that would leave the
> database in an inconsistent state".
> Is my reading correct? And, if so, do the two phrases mean the same thing?
Yes, and I believe yes. I suppose one could define things so they don't mean the same thing; however, I am not sure how one would measure update consistency without reference to the consistency of states of the database (or of whatever else is updated.) Received on Wed Apr 18 2007 - 18:45:38 CEST