Re: A pk is *both* a physical and a logical object.
Date: Wed, 18 Jul 2007 15:54:37 GMT
Brian Selzer wrote:
> "David Cressey" <cressey73_at_verizon.net> wrote in message
>>The table deosn't tell you whether a widget was moved, or whether a >>widget >>was removed, and another one inserted somewhere else. >>
> You're proving my point: it can't be determined whether it is a different
> individual or the same individual because the key value is not rigid. ...
Regarding rigidity, I would say that if we ever admit a value to be not rigid, further investigation becomes pointless and we are lost.
p Received on Wed Jul 18 2007 - 17:54:37 CEST