Database: train_station

Question: Show the station name with at least two trains.
SQL: SELECT T2.name FROM train_station AS T1 JOIN station AS T2 ON T1.station_id  =  T2.station_id GROUP BY T1.station_id HAVING count(*)  >=  2

Question: Show all locations with only 1 station.
SQL: SELECT LOCATION FROM station GROUP BY LOCATION HAVING count(*)  =  1

Question: Show station names without any trains.
SQL: SELECT name FROM station WHERE station_id NOT IN (SELECT station_id FROM train_station)

Question: What are the names of the stations which serve both "Ananthapuri Express" and "Guruvayur Express" trains?
SQL: SELECT T2.name FROM train_station AS T1 JOIN station AS T2 ON T1.station_id  =  T2.station_id JOIN train AS T3 ON T3.train_id  =  T1.train_id WHERE T3.Name  =  "Ananthapuri Express" INTERSECT SELECT T2.name FROM train_station AS T1 JOIN station AS T2 ON T1.station_id  =  T2.station_id JOIN train AS T3 ON T3.train_id  =  T1.train_id WHERE T3.Name  =  "Guruvayur Express"

Question: Find the names of the trains that do not pass any station located in London.
SQL: SELECT T2.name FROM train_station AS T1 JOIN train AS T2 ON T1.train_id  =  T2.train_id WHERE T1.station_id NOT IN (SELECT T4.station_id FROM train_station AS T3 JOIN station AS T4 ON T3.station_id  =  T4.station_id WHERE t4.location  =  "London")