Re: Designer 2000 and ternary relationships

[Quoted] In article <ryBBKEAfbPj3Iwym_at_coalole.demon.co.uk>,   Diane <Diane_at_coalole.demon.co.uk> wrote:
> In article <7m4reo$9gu$1_at_nnrp1.deja.com>, owais_anjum_at_my-deja.com
writes
> >I have just started using Designer 2000 and the
> >first component that I am using is the Entity
> >Relationship Diagrammer.
> >Is there a way to model ternary relationships and
> >relational attributes in ER Diagrammer ?
> >I am really stuck because most of my modeling
> >involves such scenarios.
> >
> >Thanks and please don't say that it does not
> >support these things are not supported !
> >
> >Owais Anjum
> >
> >
> >Sent via Deja.com http://www.deja.com/
> >Share what you know. Learn what you don't.
> forgive the ignorance but what are ternary relationships?
> --
> Diane
>

When two entities participate in a relationship, its a BINARY relationship. (e.g. customer buys product)

When three entities participate in one relationship, its a TERNARY relationship. (e.g. student takes course taught by teacher) P.S. that ternary relationships can not be modeled by replacing them with a series of binary relationships. All three entities HAVE to participate at the SAME time.

For participation of above three, the term used is n-ary relationship.

Owais

Sent via Deja.com http://www.deja.com/
Share what you know. Learn what you don't. Received on Thu Jul 15 1999 - 08:10:44 CEST