postgresql cascade constraints; code example

Example: 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';