What is the average rating of all the movies starring Tom Cruise?
starring Tom Cruise refers to name = 'Tom Cruise'; average rating = divide(sum(rating where name = 'Tom Cruise'), count(movieid where name = 'Tom Cruise'))
SELECT AVG(T1.Rating) FROM movie AS T1 INNER JOIN characters AS T2 ON T1.MovieID = T2.MovieID INNER JOIN actor AS T3 ON T3.ActorID = T2.ActorID WHERE T3.Name = 'Tom Cruise'