Re: Database design
Date: Thu, 23 Feb 2006 13:47:09 +0200
Message-ID: <dtk7bu$de4$1_at_emma.aioe.org>
"Alexandr Savinov" <spam_at_conceptoriented.com> wrote in message
news:43fd75ce$1_at_news.fhg.de...
> x schrieb:
> >> Anyway, I do not understand why a structure without an order
(hierarchy,
> >> multiple levels, depth etc.) cannot be characterized as flat? It is
> >> rather precise characterization (in contrast to many terms from
academic
> >> papers which are frequently simply misleading).
> >
> > third level - the relation
> > second level - the tuple
> > first level - the value
> > And each value belong to a domain also.
> >
> > How flat is this.
> Because what you wrote is actually a definition of being flat:
You said "depth", "multiple levels".
I have shown you "multiple levels".
I don't know your "definition of being flat".
> Space (say, 2-dimensional Euclidean space)
> Point (in this space, as a combination of 2 coordinates)
> Coordinate (a projection of the point on some axis)
The Euclidean space and a relations are not the same thing.
> Since there is no continuation (this space is not nested) we say it is
> flat.
YOU keep saying that.
Continuation ? At infinity ?
>We can build a non-flat space if assume that coordinates are
> themselves points with their own coordinates.
Nobody stop you to do that in the RM.
>Those coordinates could
> also be points with their own coordinates and so on.
At infinity ?
> Alternatively, we
> can continue this space hierarchy in the opposite direction (upward).
> The points from this set can be used as coordinates for points from
> another set. Those points can again be used as coordinates.
Nobody stop you to do that in the RM.
> So we call a structure flat if it can be shown equivalent to a
> n-dimensional space (without a hierarchy).
What do you mean by "an n-dimensional space is without hierarchy" ?
has at least two hierarchies:
Product
Vendor p1 p2 p3
v1 c1 c2 c3
v2 c4 c5 c6
Vendor --> Product
Product--->Vendor
Received on Thu Feb 23 2006 - 12:47:09 CET