Re: delete cascade

"David Cressey" <cressey73_at_verizon.net> wrote in message news:gQrVh.19078$Yh.11910_at_trndny03...
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> "Bob Badour" <bbadour_at_pei.sympatico.ca> wrote in message
> news:FepVh.25684$PV3.261993_at_ursa-nb00s0.nbnet.nb.ca...
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>> 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.
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> 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?
>

I would say no. Every update should leave the database in a consistent state, or it should be rejected. So I would not call such an update an "inconsistent update." But just because an update would leave the database in a consistent state doesn't mean that it should always be allowed. If a transition constraint exists that the update doesn't satisfy, then the update should be rejected because it is an "inconsistent update."

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Received on Wed Apr 18 2007 - 19:36:14 CEST