WITH tempTable(first_name,last_name,total) AS
    (SELECT first_name, last_name,
     (COUNT(DISTINCT rental.rental_id) + COUNT(DISTINCT payment_id)) AS total
    FROM customer JOIN rental USING (customer_id) JOIN payment USING (customer_id)
    GROUP BY first_name, last_name
    ORDER BY first_name asc)
    SELECT first_name, last_name, total,
    CASE
     WHEN total < 40 THEN 10
     WHEN total >= 40 AND total < 60 THEN 20
     ELSE 30
    END AS discount
    FROM tempTable;