Which cities had a higher temperature in Feb than in Jun or were a host city?
SELECT T1.city FROM city AS T1 JOIN temperature AS T2 ON T1.city_id   =   T2.city_id WHERE T2.Feb  >  T2.Jun UNION SELECT T3.city FROM city AS T3 JOIN hosting_city AS T4 ON T3.city_id   =   T4.host_city
cities with higher temperature in Feb than in Jun refers to T2.Feb > T2.Jun; host cities are identified by joining city and hosting_city tables on city_id = host_city; UNION is used to combine the results of two SELECT statements.