I have three main tables, one for persons, and another for nonpersons, which we will call a “business” here. The third table is a crosswalk table. Now, we needed an identifier, that is not an SSN (due to Fed’s new laws this year), etc.
Thus we use a simple Oracle Integer. Now, since this number can represent either a person or a business, not both, AND cannot be duplicated. Ie, we cannot have a person with an ID of #1 and a business with an ID #1, we use a shared sequence
Therefore, we have one sequence, listed in the crosswalk, and that # is listed in either the person or business table. So, to cap it off. We needed a unique identifier that can reference either a person or a business.