Unfathomable ERD Relationships

I am using Oracle Designer 1.1 for the first time. My previous experience with modeling has been with Knowledgware's IEW, using James Martin's diagramming conventions. Where did Oracle get its ERD diagram conventions? It is the most counter-intuitive convention I have ever seen. It is so confusing that even Oracle is confused.

In order to learn Oracle's technique, I created two entities in their ER Diagrammer: A "purchase order" entity on the left, and a "line item" entity on the right. Then I created a relationship signifying that one PO MAY contain none or many line items, and a line item MUST belong to only one PO. The diagrammer drew a line with a crow's foot (cf) as follows: cf with a solid line on the left end, and a dotted line on the right end.

When I created the report "Entity Relationship Diagram Details" the report seemed to accurately follow their conventions, but when I created the report "Relationships", the report displayed just the opposite cardinality and optionality. Also, the edit relationship dialog box is as confusing as the help screen associated with it. This really sucks. It seems obvious to me that Oracle is as confused with this convention as anybody else.

Who in their right mind would put FROM cardinality on opposite ends of the FROM optionality? And then in their helps only talk about relationship ENDS, because they themselves cannot talk in terms of FROM and TO? The designer, and the Oracle person who adopted this convention should be hung from the highest yardarm at dawn. How can I draw diagrams that will be readable by users, when Oracle and I cannot fathom them? Is there a way out of this?

Jack Botteron <jbotteron_at_pps.k12.or.us> Data Administrator, Portland Public Schools Portland, Oregon Received on Tue Jun 11 1996 - 00:00:00 CEST