Re: Can we solve this -- NFNF and non-1NF at Loggerheads

"Alan" <not.me_at_rcn.com> writes:

> You just redefined "atomic" as meaning "divisible". It Codd intended
> 1NF to include divisible attributes, he would have used the word
> "divisible", not "atomic".

No, when he said "atomic", he meant something else: he meant that the objects in question were atomic _with respect to the theory_. That is, his relational theory was not concerned with what those objects actually were; as far as the theory went, they were atomic. This does not mean that they have to be scalar values; they can be _anything_. However, if the value of an attribute is, say, a relation, there is nothing in Codd's theory that looks into that relation, and lets its contents affect operations on the outer, "real", relations.

However, the fact that individual values can be anything means that it is possible to nest relations, and (carefully) add operators to SQL that can span the levels, _without breaking the underlying theory_.

-tih

-- 
Don't ascribe to stupidity what can be adequately explained by ignorance.