Conditional PostgreSQL not null column.

table.sql

CREATE TABLE clients (
	id SERIAL UNIQUE,
	name varchar(255) NOT NULL,
	client_type client_type NOT NULL,
	cpf varchar(11),
	cnpj varchar(14),
	CHECK(CASE WHEN client_type = 'F' THEN cpf IS NOT NULL END),
	CHECK(CASE WHEN client_type = 'J' THEN cnpj IS NOT NULL END)
);