Re: Base Normal Form
Date: Wed, 06 Jul 2005 01:30:08 GMT
Message-ID: <AuGye.16814$pa3.328_at_newsread2.news.atl.earthlink.net>
"Jan Hidders" <jan.hidders_at_REMOVETHIS.pandora.be> wrote in message
news:shgye.137258$4T6.7275581_at_phobos.telenet-ops.be...
> David Cressey wrote:
> > I'd like to suggest a new Normal Form definition, one that I'm calling
Base
> > Normal Form, for lack of a better term.
>
> In some texts I've seen it called the UNF (unnormalized normal form) or
> the NFNF (non first normal form). To make things confusing, it is also
> equivalent with Chris Date's definition of 1NF.
>
Thanks, Jan.
I guess I'll stick with "Base Normal Form" for now. Are UNF and NFNF defined on tables or on relations?
> > I haven't defined candidate key, but I would want the definition to be
> > compatible with the definition of candidate key as used in BCNF.
>
> That's do-able. If you define a table as a list of tuples that all have
> the same attributes, then a superkey is a set of attributes K such that
> there cannot be two different positions in the table such that the
> tuples at these positions agree on the values for K. The notion of
> candidate key is then based on the notion of superkey in the usual way.
>
What's the difference between calling a table a list of tuples, and calling a table an array of tuples?
> Note that this definition is sloppy in the usual way where we ignore the
> fact that a candidate key is not so much a property of a single relation
> but rather of the set of all relations that are valid for a certain
relvar.
>
I'm hazy on the distinction between a relation and a relvar.
> > I'm speculating that this definition, together with BCNF, would be
> > sufficient to cover introductory DB design, skipping over 1NF, 2NF, and
3NF,
> > and leaving normal forms beyond BCNF for more advanced treatement.
>
> I wouldn't skip 3NF. The difference between BCNF and 3NF is an important
> one and the decision to go beyond 3NF should be an informed one.
Can you say some more about this? What are the consequences of taking a
step between 3NF and BCNF?
>
> -- Jan Hidders
Received on Wed Jul 06 2005 - 03:30:08 CEST