Re: Does Codd's view of a relational database differ from that of Date & Darwin? [M.Gittens]

mountain man wrote:
>
> There have been, there are,
> and there always will be
> NULLS in the real world.

NULLs are an abstraction and like all abstractions they do not really exist. The relevant question here is if they are necessary and useful to describe the world.

> Does this fact not conflict
> with Date's wants, and if
> so, why does Date want
> to ignore them?

They unnecessarily complicate the model. Anything that can be modeled with them can also be modeled without them, and to the extent that they are convenient this is mostly due to the fact that the possibilities for user-defined domains were too restricted.

• Jan Hidders