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

For each director, return the director's name together with the value of that rating and ignore movies whose director is NULL. Could you plot the result with a pie chart?
SELECT director, stars FROM Rating AS T1 JOIN Movie AS T2 ON T1.mID = T2.mID WHERE director <> "null"
SELECT "director", "stars" FROM "Rating" "T1" JOIN "Movie" "T2" ON "T1"."mID" = "T2"."mID" WHERE "director" <> "null"