Re: MV counterexample
Date: Tue, 11 May 2004 23:35:58 +0100
Message-ID: <9+JYkXCOVVoAFwOc_at_thewolery.demon.co.uk>
In message <40a11362$1_at_post.usenet.com>, x <x-false_at_yahoo.com> writes
>> If we want to have user-defined datatypes like "age" or "sex", the user
>> is going to have to be able to program (in some sense or other) the
>> integrity checks, therefore integrity checking must be a user-space
>> phenomenon. I just don't see how you can get round it. By definition,
>> the database itself cannot use data to do primary integrity checks - it
>> needs metadata. But the user can't provide metadata because the database
>> itself has no way of understanding it - it'll think it's data. Catch 22.
>
>Well, in the DKNF there are only two checks :
>- domain membership
>- keys enforcement
What's DKNF? :-)
>One of the problems the relational model is supposed to solve is :
>"In contrast, the problems treated here are those of data independence--the
>independence of application programs and terminal activities from: GROWTH in
>data types"
>:-)
Cheers,
Wol
-- Anthony W. Youngman - wol at thewolery dot demon dot co dot uk HEX wondered how much he should tell the Wizards. He felt it would not be a good idea to burden them with too much input. Hex always thought of his reports as Lies-to-People. The Science of Discworld : (c) Terry Pratchett 1999Received on Wed May 12 2004 - 00:35:58 CEST