How to make (bypass) foreign key on different tables?

Question

Java

So I have an OOP structure with an abstract object and its heirs. In another object there is a link to the parent class (where one of the heirs can be written), but when I tried to transfer this matter to the database, I went into a stupor, because FK roofing felts on one roofing felts on other table turns out. How is it solved?
Those. The question is about the structure of the database table.
PS I heard about polymorphic connections and that they are evil. But the problem is clearly not the first year there. How is it solved?

Answer 1

You can remove the constraint, but this is fraught with a violation of consistency.
It is possible to conditionally make redundancy in the projections of objects (tables) in the form of several reference fields and a type field.
Naturally, neither is ideal. But one way or another, one has to find a compromise between multidimensionality (OOP) and its projections (relational databases). Hence the various options for non-relational databases