SQL

postgresql delete cascade

CREATE TABLE employee(emp_id SERIAL PRIMARY  KEY, name VARCHAR(30),
	sector_fk INT NOT NULL);

CREATE TABLE process(emp_id SERIAL PRIMARY KEY, sector VARCHAR(20));

ALTER TABLE employee ADD FOREIGN KEY (sector_fk)
REFERENCES company(emp_id) ON DELETE CASCADE;

-- Deletes cascade employees referencing deleted companies
DELETE FROM company WHERE sector='industry';

how to add on delete cascade to existing table column postgres

alter table public.scores
drop constraint scores_gid_fkey,
add constraint scores_gid_fkey
   foreign key (gid)
   references games(gid)
   on delete cascade;