Re: The relational model is a wrong theory

On Friday, October 11, 2019 at 3:00:36 PM UTC+2, Roy Hann wrote:
> vldm10 wrote:
>
> > Dana utorak, 8. listopada 2019. u 20:14:05 UTC+2, korisnik James K. Lowden napisao je:
> >> On Mon, 7 Oct 2019 08:38:52 -0700 (PDT)
> >> vldm10 <vldm10_at_yahoo.com> wrote:
> >>
> >> > A man named John Smith had black hair in 2010. In 2019, his hair was
> >> > white. According to Codd's Relational model, these are two different
> >> > people.
> >>
> >> I would like to think you're being provocative just to breath some life
> >> into c.d.t. You don't truly believe what you wrote, right?
> >
> >>
> >> Codd refers to the phenomenon of
> >> "changing over time" in his 1970 paper.
> >
> > I can tell you that my grandmother said the same thing as you quoted E. Codd.
> > But she's certainly older than Codd, so the priority for that idea
> > belongs to her.
>
> You have just illustrated why a set of values has no intrinsic meaning.
> The intended meaning can be interpreted successfully only with respect
> to the agreed predicate that everyone shares. The RM takes this as
> given.
>
> I would like to think you did it deliberately, in which case, neatly
> done sir. Unfortunately it doesn't illustrate the claim you are making
> in the subject heading so it is probably an accident.
>
> Roy
>
> PS: I second James' gratitude to you for reviving c.d.t. Just try not to
> gnaw on too many imaginary bones.

I gave an example in my post. An example is from real life. So you can elaborate on your claims, in this example. My intention with this example was to point out some limitations in the Relational Model. Of course, the Relational model is better than the previous data models. I will start with C. Date definition of key:

Let R be a relation. Then candidate key for R is subset of the set of attributes of R, Key K, such that: 1. No two distinct tuple of R have the same value for K. 2. No proper subset of K has the uniqueness property.

However, my definition of the key is different and much richer. It includes the identifier of the entity and the identifier of the state of the entity. I defined the identification process - it's a whole new theory. I have defined another completely new theory that completely defines how one understands that an entity has been changed. This is what a group of Swedish scientists plagiarized and called "Anchor modeling". Most of these new scientific results have been plagiarized by this group of Swedish scientists at Stockholm University and presented as their theory.

My solution completely defines what a single object change is. RM theory and ER theory assume that any change to an object is a new object and this is reflected in the new key and the "update" of the corresponding data, which by definition means a new object.

That is the essence of my example.

Vladimir Odrljin Received on Sat Oct 12 2019 - 10:43:28 CEST