Re: 4 the FAQ: Are Commercial DBMS Truly Relational?

From: Kenneth Downs <firstinit.lastname_at_lastnameplusfam.net>
Date: Sun, 10 Oct 2004 22:01:34 -0400
Message-ID: <uhpckc.3va.ln@mercury.downsfam.net>

Gene Wirchenko wrote:

> Kenneth Downs <firstinit.lastname_at_lastnameplusfam.net> wrote:
>

>>Gene Wirchenko wrote:

>
> [snip]
>

>>>      That single, unique column is also a constrained (PK).  What
>>> happens when a key for that column is entered wrong?  Why would it be
>>> any different for another key for another unique column, say SSN?

>

>>The key fact about the Employee_ID column is that by definition it has no
>>meaning, it is correct if and only if it is unique.  It's only purpose is
>>to be unique.


> 

>      An SSN is correct iff it is unique, too.

>

Um, no. If you are entered with my SSN it is not correct even if unique.

-- 
Kenneth Downs
Use first initial plus last name at last name plus literal "fam.net" to
email me

Received on Sun Oct 10 2004 - 21:01:34 CDT