Re: MERGE as the imperative form of aggregation

From: Bob Badour <bbadour_at_pei.sympatico.ca>
Date: Tue, 17 Apr 2007 12:46:28 GMT
Message-ID: <Ek3Vh.25366$PV3.257421@ursa-nb00s0.nbnet.nb.ca>

paul c wrote:

> Bob Badour wrote:
>

>> ...
>> Brian's position simultaneously acknowledges and ignores logical 
>> identity and the information principle.
>> ...

>
> Regarding "logical identity" (a phrase that has a familiar ring even
> though I don't remember seeing a definition), does it mean anything but
> equality of values?

Logical identity depends on the equality of values. Logical identity requires one express identity as explicit values via one or more candidate keys. Codd originally expressed it as a requirement for a primary key in his 12 rules.

Selzer basically wants to have sets of state machines without identifying the state machines. Received on Tue Apr 17 2007 - 07:46:28 CDT