CREATE TABLE Reviewer (rID INT, name TEXT)
CREATE TABLE Rating (rID INT, mID INT, stars INT, ratingDate DATE)
CREATE TABLE Movie (mID INT, title TEXT, year INT, director TEXT)

Show the stars of each director by a pie chart.
SELECT director, stars FROM Rating AS T1 JOIN Movie AS T2 ON T1.mID = T2.mID
SELECT "director", "stars" FROM "Rating" AS "T1" JOIN "Movie" AS "T2" ON "T1"."mID" = "T2"."mID"