how many country participate in the market?
select count ( distinct country ) from market
how many directors of the films never presented in china?
select count ( director ) from film where film_id not in ( select film_id from film_market_estimation as t1 join market as t2 on t1.market_id = t2.market_id where country = 'China' )
how many titles were never presented in china?
select count ( title ) from film where film_id not in ( select film_id from film_market_estimation as t1 join market as t2 on t1.market_id = t2.market_id where country = 'China' )