SELECT s.country, COUNT(DISTINCT id.staff_id) FROM store s
LEFT JOIN staff id ON (s.store_id = id.store_id)
GROUP BY s.country
ORDER BY s.country;




SELECT f.title, COUNT(DISTINCT i.inventory_id) FROM film f
LEFT JOIN inventory i ON (f.film_id = i.film_id)
GROUP BY f.title
ORDER BY f.title;





SELECT f.title FROM film f
LEFT JOIN inventory i ON (f.film_id = i.film_id)
GROUP BY title
HAVING COUNT(DISTINCT i.inventory_id) = 8
ORDER BY title;





SELECT first_name, last_name FROM customer
WHERE customer_id IN (SELECT customer_id FROM rental
                      WHERE rent_date < return_date)
ORDER BY first_name,last_name ;