Re: Question re: Practical Issues in Database Management

Carlos M. Calvelo wrote:
> On 22 mrt, 00:49, Joe Thurbon <use..._at_thurbon.com> wrote:

>> I've had a look on the dbdebunk website, but errata are only available
>> via email. As far as I'm aware, the site is no longer kept active.
>>
>> Does anyone know if the errata are available through another means?
>>

Hmm, an update anomaly?

Thanks Carlos.

To all:

It seems to me that neither of the errata I've been pointed to address the issue that I originally mentioned in this thread. Namely, that the definitions of multivalued dependencies and 4th normal form given in the book seem to be overly strict.

In particular, if a multivalued dependancy is defined as:

"A MVD between two columns exists when sets of values in one column are each associated with values in another column"

and 4th normal form is defined as

"If no MVDs exist between columns, then a table is in 4th normal form"

Even assuming that 'no MVDs' is shorthand for 'no MVDs that are not also FDs' these definition would mean that the table,

EMP# ACTIVITY

130      DEBUG
130      SUPPORT

would not be in 4th normal form. (Since, it's clear that there is a set of values {DEBUG, SUPPORT} that is functionally dependant on EMP#. The caption of the example on page 138 says that the above table is in 4th normal form (as do all other definitions I've read).

Have I found an error in the book (unlikely). And if not, what am I missing?

Cheers,
Joe Received on Thu Mar 22 2007 - 22:03:29 CET