roller

    CREATE TYPE school_type AS ENUM ('college', 'high_school');
    CREATE TABLE schools (
      id SERIAL PRIMARY KEY,
      type school_type,
      unique (id, type)
    );
    CREATE TABLE colleges (
      id INTEGER NOT NULL,
      type school_type default 'college',
      check (type='college'),
      foreign key (id, type) references school(id, type)
    );

    foreign key (id, 'college') references school(id, type)