Re: RM VERY STRONG SUGGESTION 4: TRANSITION CONSTRAINTS

On 09/09/2010 2:37 PM, Brian wrote:
...
>
> I suggest you read Hugh Darwen's book, /An Introduction to Relational
> Database Theory/. It's available for download online. See the TTM
> web site. After you read his book. Maybe you'll understand how
> ridiculous this post makes you sound.
>
> As for having a mental block. Trying to model database updates using
> functional programming is like trying to milk a steer. Good luck with
> that!

No doubt trying either is just as shaky as your mutant tuples (I'm surprised you don't just refer to muples or m-tuples, we'd all save much time). Obviously implementers shouldn't try, better to implement with nothing but replacement in mind, avoiding all notion of sequence which is perhaps the obstacle that most programmers waste the most time coping with (implementers too!).

Darwen, like Codd, uses phrases like "vary from time to time", by way of explaining results, nothing wrong with that. The mistake many, maybe most, people make is to read that and think that an implementation is somehow destined to mimic every last figure of speech in the description.

(Sometimes I wonder if a kind of orthogonality might apply to other dimensions besides operator side-effects. Given the baby steps the db field is still limited to and the mass confusion so evident on most db sites, I think it's far safer to leave assignment, probably sequence too, out of the programming picture and let the environment control that context.) Received on Fri Sep 10 2010 - 00:30:45 CEST