CREATE TABLE film_market_estimation (estimation_id NUMBER, low_estimate NUMBER, high_estimate NUMBER, film_id NUMBER, type CLOB, market_id NUMBER, year NUMBER)
CREATE TABLE market (market_id NUMBER, country CLOB, number_cities NUMBER)
CREATE TABLE film (film_id NUMBER, title CLOB, studio CLOB, director CLOB, gross_in_dollar NUMBER)

Which studios have never worked with the director Walter Hill?
SELECT studio FROM film EXCEPT SELECT studio FROM film WHERE director = "Walter Hill"
SELECT "studio" FROM "film" EXCEPT SELECT "studio" FROM "film" WHERE "Walter Hill" = "director"