How do you deal with polymorphism in a database?

Question

Example

I have Person, SpecialPerson, and User. Person and SpecialPerson are just people - they don\

Answer 1

In our company we deal with polymorphism by combining all the fields in one table and its worst and no referential integrity can be enforced and very difficult to understand model. I would recommend against that approach for sure.

I would go with Table per subclass and also avoid performance hit but using ORM where we can avoid joining with all subclass tables by building query on the fly by basing on type. The aforementioned strategy works for single record level pull but for bulk update or select you can't avoid it.