Roy Hann wrote:
> "Brian Selzer" <brian_at_selzer-software.com> wrote in message
> news:oXdni.23174$Rw1.4623_at_newssvr25.news.prodigy.net...
> [snip]
>
>>>You can call what the user issued an update, if you care to, but what
>>>really happened is that an individual, identified by the before value of
>>>the key, was deleted, and a new individual, identified by the after
>>>value
>>>of the key was inserted. The fact that the old value and the new value
>>>used
>>>the same storage ("row", if you like) is irrelevant. They are
>>>different
>>>values, and they designate different individuals.
>>
>>Not so. Consider the following statement:
>>
>> I moved the widgit with lot number 203 at location 22 to location 44.
>
> What is the so-called "individual" here? The widget, the lot number or the
> location? You've told us the key is the entire header, so it is
> irreducible, so none of these is inescapably unique in this table.
>
>
>>Now assuming that there can only be one widgit from the same lot at a
>>particular location, then the definite description before the update,
>>
>> the widgit with lot number 203 at location 22
>>
>>refers to the same widgit as the definite description after the update,
>>
>> the widgit with lot number 203 at location 44.
>>
>>If there is also a rigid designator, then the situation becomes clear:
>>
>>before the update, these all denote the same individual:
>>
>> the widgit with serial number 123 and with lot number 203 at location 22
>> the widgit with serial number 123
>> the widgit with lot number 203 at location 22
>>
>>which is the same individual as these:
>>
>> the widget with serial number 123 and with lot number 203 at location 44
>> the widget with serial number 123
>> the widget with lot number 203 at location 44
>>
>>after the update.
>>
>>So, if relation widgits {lot_number, location}
>>has a tuple {lot_number=203, location=22}
>
> How the heck does this tuple represent *anything* about widget 123 (or any
> other particular widget) if the serial number isn't an attribute? The only
> way it can do that is if you first assert your entire relation represents
> propositions about the widget with serial number 123 exclusively. That's
> fair enough and I'd have no problem with it, but you aren't saying that.
>
>
>>and an update is issued:
>>
>>UPDATE widgits SET location=44 WHERE lot_number = 203 AND location=22
>>
>>Then the resulting relation has a tuple
>>
>>{lot_number=203, location=44}
>>
>>that refers to the same individual as the tuple
>>
>>{lot_number=203, location=22}
>>
>>before the update.
>
> I am now satisified that you are talking nonsense. Erudite-sounding
> nonsense but still nonsense.
What the heck took you so long?
Received on Wed Jul 18 2007 - 07:26:01 CDT
