Re: On Normalisation & the State of Normalisation

On Tuesday, February 3, 2015 at 5:59:04 AM UTC-8, com..._at_hotmail.com wrote:
> I just find it amusing that the particular application plus no interpretation of tables tells us that there is a universal relation CK that this diagram fails to express.

Here's what I failed to express earlier:

An envelope gets to a particular address. Ids do not appear on an envelope. So joining an appropriate set of tables and projecting out id columns gives rows 1:1 with Address AddressIds. So there is a join CK among the non-id columns. But this set of tables gives no such CK. So they are not appropriate.

(The FKs correspond to FDs on the CK in the join. So there is a CK among the non-id columns of Street and Address.)

PS:

Of course, that claim does not arise from a particular (normalization or design) process. So it proves nothing about the adequacy of any allegedly adequate process. Nor would any claims about the design without giving a process and sound reasoning.

To show that an alleged process is adequate one need only give it and either a counterexample or sound justification. Of course, one would only soundly believe it inadequate if they had already done so. (Granted, after demonstrating enough examples of inadquate processes from a group one might reasonably claim that the group didn't have an adequate process.)

Of course, that's not showing that an allegedly adequate process actually is. That requires giving it and a sound justification.

philip Received on Thu Feb 05 2015 - 22:58:12 CET