Re: Designer/2000 ERD Cardinalities

The ERD methodology is documented in a book by one Richard Barker

Jeff Jacobs wrote:
>
> rgordon_at_acpub.duke.edu (Robert Gordon) wrote:
>
> The notation is unique to Oracle. I happen to like it, as it reduces the number
> of symbols hanging on the line, and also focuses on "optionality" of the
> relationship instead of "minimum cardinality".
>
> Focusing on the line half closest to the entity also lets you know the
> optionality of the resulting FK columns...
>
> The notation uses "MUST BE" and "MAY BE" in place of "zero..." when reading the
> relationships.
>
> >
> >> Jeffrey Jacobs & Associates
> >
> >This is the opposite of what I initially thought. It seemed intuitive
> >that the half of the line closer to the crows foot would indicate
> >optionality at that end (like IE). BTW, is Oracle using a methodology
> >I just haven't learned or did they make this up to confuse people?
> >
> >Thanks Jeff
> >
> >
> >> Oracle Designer/2000 Consulting & Training
> >> 951-2 Old Country Road, Suite 119, Belmont, CA 94002
> >> Voice: 415-571-7092, FAX: 800-665-1379 CompuServe: 76702,456
> >> Internet: jmjacobs_at_ix.netcom.com
> >>
> >>
> >
> >
> >- Robert Gordon
> >
>
> -JJ
>
> Jeffrey Jacobs & Associates
> Oracle Designer/2000 Consulting & Training
> 951-2 Old Country Road, Suite 119, Belmont, CA 94002
> Voice: 415-571-7092, FAX: 800-665-1379 CompuServe: 76702,456
> Internet: jmjacobs_at_ix.netcom.com
>
>
 

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