Re: I think my book may be wrong about cardinality, but I'm not sure

paul c <toledobythesea_at_oohay.ac> wrote:

[snip]

>Just a side question, since I see the term "N-ary relationship" quite
>often. If a relation has N attributes, doesn't it implement (2**N)-1 or
>2**N relationships or thereabouts? Or is that what the term means and
>I've been misunderstanding it all this time?

     It means something else. It is the count of relations related (with the understanding that a relation could appear more than once and thus be counted more than once).

          invoice to client: 2-ary
          part number to warehouse to client: 3-ary

Sincerely,

Gene Wirchenko

Computerese Irregular Verb Conjugation:

     I have preferences.
     You have biases.
     He/She has prejudices.