Context: CREATE TABLE farm_competition (Host_city_ID VARCHAR); CREATE TABLE city (Official_Name VARCHAR, City_ID VARCHAR)
Question: Show the official names of the cities that have hosted more than one competition.
Answer: SELECT T1.Official_Name FROM city AS T1 JOIN farm_competition AS T2 ON T1.City_ID = T2.Host_city_ID GROUP BY T2.Host_city_ID HAVING COUNT(*) > 1