Resolving Supertypes and Subtypes in the Database Design Transformer
421293Feb 12 2009 — edited Mar 15 2010Hi,
I have a design question re. converting Logical to Physical Data Models in Designer.
For the mapping approach from my ERD to my SMD, I chose the Implicit Subtype Implementation, i.e. separate tables for each subtype and for the supertype. However, the subtypes have all the supertype columns. I wondered why Designer enforces this? It makes my SMD very cluttered. I would prefer to have the supertype columns in the supertype only.
But, before you ask, I know this can be avoided by chosing the Arc Implementation. The problem I have with this approach is that the supertype has a separate FK column for each subtype. I am potentially dealing with many subtypes (50+), so am concerned about the number of null id columns in the supertype table. (Have used this approach before, but with only a handful of tables.)
Thanks,
Antony