CREATE TABLE track (name VARCHAR, track_id VARCHAR)
CREATE TABLE race (track_id VARCHAR)

Show the name of track with most number of races.
SELECT T2.name FROM race AS T1 JOIN track AS T2 ON T1.track_id = T2.track_id GROUP BY T1.track_id ORDER BY COUNT(*) DESC LIMIT 1
SELECT "T2"."name" FROM "race" AS "T1" JOIN "track" AS "T2" ON "T1"."track_id" = "T2"."track_id" GROUP BY "T1"."track_id" ORDER BY COUNT(*) DESC NULLS LAST LIMIT 1