CREATE TABLE flight (id VARCHAR2, airport_id VARCHAR2, pilot VARCHAR2)
CREATE TABLE airport (id VARCHAR2, airport_id VARCHAR2, pilot VARCHAR2)

How many airports haven't the pilot 'Thompson' driven an aircraft?
SELECT COUNT(*) FROM airport WHERE NOT id IN (SELECT airport_id FROM flight WHERE pilot = 'Thompson')
SELECT COUNT(*) FROM "airport" WHERE NOT "id" IN (SELECT "airport_id" FROM "flight" WHERE "pilot" = 'Thompson')