FairFunk (7/16/2010)
How ever what would happen further down the line when it comes to implementing the design and if I decide not to roll up the subtypes to the supertype. That would leave me with 4 tables (organisation, charity, company and trust) and the same column "registered address" defined in two separate tables.
Physical implementation is a different animal 🙂
I would probably implement this at the Supertype level, meaning I'll create a single ORGANIZATIONS table to describe Companies, Charities and Trusts. This table will include both primary_address and registered_address columns.
So... where are the subtypes? I'll include an organization_type column in ORGANIZATIONS table to document what kind of organization is being described in each row.
Does it makes sense?
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Pablo (Paul) Berzukov
Author of Understanding Database Administration available at Amazon and other bookstores.
Disclaimer: Advice is provided to the best of my knowledge but no implicit or explicit warranties are provided. Since the advisor explicitly encourages testing any and all suggestions on a test non-production environment advisor should not held liable or responsible for any actions taken based on the given advice.