#sql

result.png

TPT.sql

-- model inheritance in database
-- table per type
-- https://stackoverflow.com/a/190306

CREATE TABLE users (
	id SERIAL,
	email VARCHAR(50) NOT NULL,
	password VARCHAR(20) NOT NULL,
	
	PRIMARY KEY (id)
);

CREATE TABLE employees (
	id INTEGER,
	cpf CHAR(11) NOT NULL,
	
	PRIMARY KEY (id),
	FOREIGN KEY (id) REFERENCES users (id)
);

INSERT INTO users (email, password) VALUES (
	'j@gmail.com',
	'pass1234'
);

INSERT INTO employees VALUES (
	1,
	'01234567890'
);

CREATE TABLE employers (
	id INTEGER,
	cnpj CHAR(11) NOT NULL,
	
	PRIMARY KEY (id),
	FOREIGN KEY (id) REFERENCES users (id)
);

INSERT INTO users (email, password) VALUES (
	'k@gmail.com',
	'pass1234'
);

INSERT INTO employers VALUES (
	2,
	'98765432101'
);

-- select all users (both employees and employers)
SELECT users.id, email, password, cpf, cnpj FROM users
	LEFT JOIN employees ON users.id = employees.id
	LEFT JOIN employers ON users.id = employers.id;