I assume you want to delete referential data without worrying about deleting it in just the right order to preserve references in intermediate steps. I wouldn't drop and add a foreign key just to ...

I'm adding a table and subclass table to my DB. (Subclass table = table where the primary key joins to the primary key of another table, to give extra row information to some subset of the rows.

A primary key is a field used to uniquely identify every record in the database. Sometime primary keys are obvious, for example a car license plate could be used to uniquely identify cars. Often, ...