Re: the two questions

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?

> 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?

-- 
Jonathan Leffler                   #include <disclaimer.h>
Email: jleffler_at_earthlink.net, jleffler_at_us.ibm.com
Guardian of DBD::Informix v2007.0914 -- http://dbi.perl.org/

ptb/PTB-1860 whirlpool2 2007-11-24 00:00:06
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