Question

I have a table which contains two type of data, either for Company or Employee.

Identifying that data by either ‘C’ or ‘E’ & a column storing primary key of it.

So how can I give foreign key depending on data contained & maintain referential integrity dynamically.

id | referenceid  | documenttype 
-------------------------------
1  | 12           | E 
2  | 7            | C 

Now row with id 1 should reference Employee table with pk 12 & row with id 2 should reference Company table with pk 7.

Otherwise I have to make two different tables for both.
Is there any other way to accomplish it.

Answer 1

If you really want to do this, you can have two nullable columns one for CompanyId and one for EmployeeId that act as foreign keys.

But I would rather you to try and review the database schema design.