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

For each director, return the highest rating among all of their movies and the value of that rating, group by director in a scatter, and Ignore movies whose director is NULL.
SELECT stars, MAX(T1.stars) FROM Rating AS T1 JOIN Movie AS T2 ON T1.mID = T2.mID WHERE director <> "null" GROUP BY director
SELECT "stars", MAX("T1"."stars") FROM "Rating" AS "T1" JOIN "Movie" AS "T2" ON "T1"."mID" = "T2"."mID" WHERE "director" <> "null" GROUP BY "director"