Re: Dawn doesn't like 1NF

On Thu, 7 Oct 2004 08:48:55 -0400, "Laconic2" <laconic2_at_comcast.net> wrote:

>Having said that, there is a fundamental divergence beween relational
>calculus and first normal form as described by Codd in his 1970 paper. If
>you reread the 1970s paper carefully, you'll see that 1NF consists of two
>parts:

If you read carefully, you'll see that there is not any mention to 1NF.

>But the limitation to simple attributes has no such counterpart in the
>mathematics of relations. In particular, a domain can be a domain of
>relations in math. Not in the relational data model of 1970.

The problem is that "simple" and "atomic" are not precise terms.

For instance: Are strings simple or complex?

>them required that table columns be "simple". Even a blob is "simple" from
>the point of view of the DBMS. From the DBMS point of view, it's just a
>string bytes with no discernable substructure.

An string of characters has a discernable structure. It is an ordered list of (n) chars.

Regards Received on Thu Oct 07 2004 - 17:23:05 CEST