Re: A Normalization Question

> Once you understand why we normalize you will understand why the notion of
> redundancy is defined in database theory as it is and why multiple
> occurrences of the same string in a data structure are not
> necessarily redundant.

Multiple occurances of the same string is necessarily redundant. It requires a limited data model and definitions to obscure this fact.

> > [...] Suppose, the world is taken oven by islamic terrorist. As part
> > of their spoils, they want every word in every computer to be spelled
> > backwards, thus 'brown' needs to be update to 'nworb'. [...] In the
> > above tuple, updating one and not the others, corrupts the db.
>
> Yes, but only when you start from an instance that is not already an
> instance from the new database schema is concerned. To show that either
> instances of the new or the old database schema have redundancy you have
> to demonstrate that there are update anomalies that stay within that
> particular database schema.

In my data model, the data is the schema; however more general schemas could be derived from the data if needed. I am not sure what point you are making, but changing one 'brown' to 'nworb' in a db with multiple occurances of the same string results in an update anomaly. Received on Tue Jul 13 2004 - 00:54:08 CEST