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@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 - 11:45:38 CDT