Re: delete cascade

From: Bob Badour <bbadour_at_pei.sympatico.ca>
Date: Mon, 16 Apr 2007 12:56:51 GMT
Message-ID: <noKUh.25015$PV3.252069@ursa-nb00s0.nbnet.nb.ca>

paul c wrote:

> Bob Badour wrote:
>

>> paul c wrote:
>>
>>> I sometimes wonder why the above noun used in place of an adjective 
>>> is needed.    When the table/relation definition of a line item 
>>> references an invoice number can it mean anything other than that the 
>>> line item doesn't exist unless the invoice exists?  Ie., why 
>>> shouldn't delete always mean so-called "cascade"?
>>>
>>> (just trying to keep Marshall interested.)
>>
>>
>> Because some times it means: "If a line item exists, the invoice must 
>> also exist."

>
>
> Please forgive my thickness, but doesn't "line item doesn't exist
> unless..." (ie., "only if") "...the invoice exists" mean the same?

No. One states that deleting the invoice automatically deletes any items that exist. The other states that one may not delete an invoice when any items exist. Received on Mon Apr 16 2007 - 07:56:51 CDT