How to do single-table inheritance when discriminator is in another table?

Question

Suppose you have a table called PERSONS and it stores entities which you want to model via various subclasses of Person based on a simple discriminator column OCCUPATION: "D"=>Doctor, "L"=>Lawyer, etc. So far so good.
Now suppose that the DBA is going to remove the OCCUPATION column and replace it with a column called OCODE, where "01"..."50"=>Doctor, "51"..."70"=>Lawyer, etc. There will be a second table, OCODE_TO_OCCUPATION, which can be used via a join to recover the old OCCUPATION column in SQL.
From the DBA's perspective, everything is fine. From mine, it breaks EJB3's ability to map the table's contents into object of the appropriate classes. It seems like EJB3 would need to support one of the following:
(1) Multiple discriminator values per class ("01".."50" => Doctor, etc.).
(2) Ability to provide my own object factory so that I can do the OCODE-to-OCCUPATION mapping myself.
(3) Ability to use a view which provides the discriminator column when querying, while still using the real table for insert/update/delete.
Is there a way I can get the old class structure given the new table structure?

Answer 1

As I understand it, you can have exactly ONE discriminator value per class. I'm certainly not going to define 100 classes. There are 50 discriminator values that map to class "Doctor".