Confusion between Roles and Facts
Date: 9 Oct 2003 09:36:12 -0700
Message-ID: <917a4b28.0310090836.4fc157d9_at_posting.google.com>
I am using Visio for EA that came with VS.NET 2003. I am a novice ORM modeler, and I am confused between what I see in the round-trip between the ORM Concept and Logical Model.
I have a User object and a Role object. I pull them from the Object types view onto my page and pull a predicate from the ORM source shapes. I connect them up, stating that a User can have 0+ Roles and Roles can have 0+ Users. However, I don't understand how to describe how that relationship has Active and Inactive Dates, so I go to my logical model, build my project and see a table created that has the two keys for those objects as a composite primary key. I change it so that it has its own primary key and that those keys are required, and add my active/inactive dates. Pushing it back to the ORM model, I see a new object (UserRole), along with the new value objects.
Here's my problem:
1. It appears that it is saying that I should have thought of UserRole
as an object to begin with. However, my understanding of ORM is that
I should NOT think of Table=Entity and Field=Value. Where is my wrong
thinking?
2. What I REALLY want is a restraint that says that I can have only ONE combination of User and Role for any datepoint (respecting the Active/Inactive dates). I understand that I cannot do that in ER and have to rely on triggers on my DB. Is there any way to express that in ORM?
Thank you for your patience.
Kevin Nechodom
University of Utah
Received on Thu Oct 09 2003 - 18:36:12 CEST