Re: What are Closing and Normalization?
Date: Mon, 13 Jan 2003 21:01:27 GMT
Message-ID: <H8o7qE.C6C_at_news.boeing.com>
"Jonathan Leffler" <jleffler_at_earthlink.net> wrote in message
news:3E20A87E.1000203_at_earthlink.net...
> Jim Kennedy wrote:
> > Search google for Codds rules.
>
[snip]
> I suspect that the 'closing' referred to should be 'closure'. Put
> simply (and hence non-rigorously), closure is the property of the
> relational algebra (or calculus) which says that all results from
> relational operations on tables are themselves tables. It is similar
> to the closure property of arithmetic, where the result of a
> computation involving numbers is another number (with exceptions for
> divide by zero and maybe other odd-ball cases).
It might be that 'closing' could alternatively refer to the closure set of dependencies or to the closure set of attributes (usually introduced and covered in tandem with the formalisms of normalization and normal forms).
Warmest Regards,
Daniel Guntermann
> --
> Jonathan Leffler #include <disclaimer.h>
> Email: jleffler_at_earthlink.net, jleffler_at_us.ibm.com
> Guardian of DBD::Informix 1.04.PC1 -- http://dbi.perl.org/
>
Received on Mon Jan 13 2003 - 22:01:27 CET