Re: Sixth normal form

From: paul c <toledobythesea_at_oohay.ac>
Date: Thu, 02 Aug 2007 02:59:05 GMT
Message-ID: <ZLbsi.23504$fJ5.6912@pd7urf1no>

Brian Selzer wrote:
> "paul c" <toledobythesea_at_oohay.ac> wrote in message
> news:xV5si.22613$rX4.14717_at_pd7urf2no...
>

>>Brian Selzer wrote:
>>...
>>
>>>It's somewhat unrelated, ...
>>
>>I was with you up 'til the first comma in the last paragraph.  It sure 
>>doesn't have to do with redundancy.  First there were rigid keys, then 
>>contingent keys, now we have immune keys.  Newcomers please note - don't 
>>believe this mumbo-jumbo, it is all undefined mysticism, as is the term 
>>"key update".
>>

>
>
> Are you saying that Codd's use of "key update" in his definitive1970 paper
> was also mumbo-jumbo?
> ...

Yes.

> Isn't it strange that people who can't come up with a solid argument resort
> to misrepresentation, nitpicking over terminology, and outright derision.
> Often they end up with their foot in their mouth.
> ...

No, it isn't strange to me, I see it all the time.

>

>>Also, I would like to know if anybody has ever invented a relational 
>>algebra or calculus that supports "update".  AFAIK, update is either a 
>>system colloquial, environmental or a language, say SQL, term.  Yeah, I 
>>know people say "update" a tuple et cetera and I think that's okay if it 
>>is agreed and understood just what exactly the system or dbms they have in 
>>mind is going to do about the "update".  In the recent threads, I don't 
>>and I'm pretty sure we don't either.
>>

>
>
> It should be obvious that relational algebra and calculus are meant for
> queries, not updates. Unlike the operators of relational algebra, neither
> insert, update, nor delete returns a result. Nor does relational
> assignment. More importantly, the algebra and the calculus involve a single
> database value (set of relation values), a snapshot of reality if you
> prefer. An update operator (as D&D call them) involves two snapshots of
> reality, and truth in one does not imply truth in the other.
>
> Before you make a complete fool of yourself, I suggest you read Codd's 1990
> book. You should be able to find it online now. I did. I can't remember
> where, though.
> ...

Let me know if you remember. A salesman stole mine.

p Received on Wed Aug 01 2007 - 21:59:05 CDT