text: CREATE TABLE public.pre_contacts
  (
      a_id        INTEGER NOT NULL,
      b_id        INTEGER NOT NULL,
      message     VARCHAR(100),
      updated_at  TIMESTAMP WITHOUT TIME ZONE NOT NUlL,
      created_at  TIMESTAMP WITHOUT TIME ZONE NOT NUlL,
      FOREIGN KEY (a_id) REFERENCES users(id) ON UPDATE NO ACTION ON DELETE CASCADE,
      FOREIGN KEY (b_id) REFERENCES users(id) ON UPDATE NO ACTION ON DELETE CASCADE
  )
  WITH (
    OIDS = FALSE
  );
  CREATE INDEX pre_contacts_id_index ON pre_contacts(a_id, b_id);