Consider the following relational model for a movie database. The basic information of movies, actors, and directors is stored in the Movie, Actor, Director tables, respectively. The Direction table keeps track of the relationships between movies and directors, while the Cast table keeps track of the relationships between movies and actors.

Movie(mov_id: integer, title:string, year:integer, country:string)
Cast(act_id: integer, mov_id: integer, role: integer)
Actor (act_id: integer, act_name:string)
Direction(dir_id: integer, mov_id: integer)
Director (dir_id: integer, dir_name:string)

The foreign key references are listed here:
Cast. act_id→ Actor. act_id
Cast. mov_id → Movie. mov_id
Direction. dir_id→ Director. dir_id