text: SELECT first_name FROM actor
  UNION
  SELECT first_name FROM customer;
  
  SELECT first_name FROM actor
  INTERSECT
  SELECT first_name FROM customer;
  
  SELECT first_name FROM actor
  EXCEPT
  SELECT first_name FROM customer;
  
  SELECT first_name FROM actor
  UNION ALL
  SELECT first_name FROM customer;
  
  SELECT first_name FROM actor
  INTERSECT ALL
  SELECT first_name FROM customer;
  
  SELECT first_name FROM actor
  EXCEPT ALL
  SELECT first_name FROM customer;
  