On Fri, Nov 14, 2008 at 8:49 AM, metastable <listpit@stripped
> This is where it gets nasty. A customer may be a human being or a
> company. I see different approaches here:
> 1) keep customer tables separate, based on which type of customer it is
> 2) create the customer table with a column specifying if we're dealing
> with a human being or a company
> 3) create the customer table with a FK for people and a FK for
> companies, and decide on the customer type in the application based on
> the presence of that key
You're making it more complicated than it needs to be.
A customer may be either a person or a company.
Your customers table may contain columns that are the union of what is
required for a person and what is requried for a company, plus of course an
enumerated value that indicates which the customer is and indirectly which
columns are populated for a given row.
Problem solved. Over time, several square millimeters on a disk wasted.