SELECT count(*) FROM visitor WHERE id NOT IN (SELECT t2.visitor_id FROM museum AS t1 JOIN visit AS t2 ON t1.Museum_ID  =  t2.Museum_ID WHERE t1.open_year  >  2010)
Find the number of visitors who did not visit any museum opened after 2010.
SELECT count ( * ) FROM visitor WHERE id NOT IN ( SELECT t2.visitor_id FROM museum AS t1 JOIN visit AS t2 ON t1.Museum_ID = t2.Museum_ID WHERE t1.open_year > 2010 )
select count ( * ) from visitor where id not in ( select t2 . visitor_id from museum as t1 join visit as t2 on t1 . museum_id = t2 . museum_id where t1 . open_year > value )
Find the number of visitors who did not visit any museum opened after 2010 .