Give the full name of the actor who acted the most in drama movies?
full name refers to first_name, last_name; drama is a category of a film; acted the most in a movies refers to MAX(COUNT(film_id))
SELECT T.first_name, T.last_name FROM ( SELECT T1.first_name, T1.last_name, COUNT(T2.film_id) AS num FROM actor AS T1 INNER JOIN film_actor AS T2 ON T1.actor_id = T2.actor_id INNER JOIN film_category AS T3 ON T2.film_id = T3.film_id WHERE T3.category_id = 7 GROUP BY T1.first_name, T1.last_name ) AS T ORDER BY T.num DESC LIMIT 1