Re: Designer/2000 ERD Cardinalities

[Quoted] rgordon_at_acpub.duke.edu (Robert Gordon) wrote:

>Could someone please explain the cardinality symbols for D/2000 ERD's?
>I am familiar with IDEF1X and IE symbologies, but I cannot figure this
>out - particularly which end is which for the different symbols (and I
>have RTFM)! Thanks
>
>
>- Robert Gordon
>

[Quoted] The crow's foot/trident is the same as in IE notation for "more than one". D2K uses dashed and solid lines to indicate optionality/minimum cardinality. The line is divided into two "halves"; the half _closest_ to the entity indicates the optionality for that direction. Solid line is "mandatory", dashed is optional. So you have to combine the line half closest to the entity with the presence/absence of a crow's foot at the _other_ end to arrive at your optionality + maximum cardinality.

[Quoted] The line type replaces the "o" and "|" in IE notation. The "|" in D2K is used to indicate that the relationship is part of the unique identifier.

-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     Received on Thu Jan 02 1997 - 00:00:00 CET