Re: the two questions

On Nov 23, 9:32 pm, Jonathan Leffler <jleff..._at_earthlink.net> wrote:
> vldm10 wrote:
> > Not long time ago on this NG there were few posts which involved an
> > entity with 200+ attributes.
> > Let all these attributes satisfy the following two conditions:
> > 1) All these attributes are mutually independent
>
> I have a feeling you are going to need to recast your conditions. If
> all the attributes are mutually independent, then the only candidate key
> for the relation is the combination of all N attributes, is it not?

Yes, but at least 200 attributes. I mean it should be more then 200 regarding condition 2). Condition 2) in fact involves "Temporal DB" considerations.

>
> > 2) Every attribute of an entity can change its value - like in
> > "Temporal DB"
>
> > Now I have two questions:
>
> > 1) How many attributes has a key of the corresponding relation?
> > 2) How many attributes has a key of m-n relationship between the two
> > mentioned entities?
>
> Two entities? Where did the second one appear from? You started with
> an entity with 200+ attributes, and ... magic'd a second one out of thin
> air?

Let it be the two entities, so that we can make m-n relationship.

>
> --
> Jonathan Leffler #include <disclaimer.h>
> Email: jleff..._at_earthlink.net, jleff..._at_us.ibm.com
> Guardian of DBD::Informix v2007.0914 --http://dbi.perl.org/
>
> ptb/PTB-1860 whirlpool2 2007-11-24 00:00:06
> 88FCD1C504D5345557AF5FEA2991A9138F5D151C781AC5FC296732F1BFDA6C7371B115
> AB2B27673813EC1EE5320A28C938AA7316F4FCD544113EF4ABD4C9C9A
Vl. Odrljin Received on Sat Nov 24 2007 - 05:47:33 CET