Are foreign keys really necessary in a database design?

Question

As far as I know, foreign keys (FK) are used to aid the programmer to manipulate data in the correct way. Suppose a programmer is actually doing this in the right manner alr

Answer 1

They are not strictly necessary, in the way that seatbelts are not strictly necessary. But they can really save you from doing something stupid that messes up your database.

It's so much nicer to debug a FK constraint error than have to reconstruct a delete that broke your application.