List the name for all stations.
select name from station
Also count the number of trains for each.
select t2.name, count(*) from train_station as t1 join station as t2 on t1.station_id = t2.station_id group by t1.station_id
Show those names with at least two trains.
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