Re: RM VERY STRONG SUGGESTION 4: TRANSITION CONSTRAINTS

From: Bob Badour <bbadour_at_pei.sympatico.ca>
Date: Sat, 04 Sep 2010 01:03:44 -0300
Message-ID: <4c81c52b$0$11815$9a566e8b_at_news.aliant.net>



Bob Badour wrote:

> Brian wrote:
>

>> On Sep 3, 2:29 pm, Erwin <e.sm..._at_myonline.be> wrote:
>>
>>> On 3 sep, 17:35, Brian <br..._at_selzer-software.com> wrote:
>>
>> <snip>
>>
>>>> UPDATE is not the same as a combination of DELETE-then-INSERT, but not
>>>> because of some objectid.
>>>
>>> It is the same.  Always.  Before some update, relvar R has value
>>> {t1}.  After that update, relvar R has the value {t2}.
>>>
>>> Please explain what the difference is between this update and a
>>> multiple assignment consisting of the delete of t1 and the insert of
>>> t2.
>>
>> In the update, the referent of t1 is the referent of t2, but in the
>> multiple assignment, the referent of t1 ceased to exist and the
>> referent of t2 came into existence.  The "meaning" of the fact "t2" is
>> therefore different.  For example,

>
> I disagree. At the logical level of discourse, both assignments are the
> same.

WTF? How did Selzer get out of my filter? Received on Fri Sep 03 2010 - 23:03:44 CDT

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