Table schema:
CREATE TABLE train (Railway_ID VARCHAR); CREATE TABLE railway (Builder VARCHAR, Railway_ID VARCHAR)

Question: Show the id and builder of the railway that are associated with the most trains.
SQL: SELECT T2.Railway_ID, T1.Builder FROM railway AS T1 JOIN train AS T2 ON T1.Railway_ID = T2.Railway_ID GROUP BY T2.Railway_ID ORDER BY COUNT(*) DESC LIMIT 1