CREATE TABLE stadium (name VARCHAR, id VARCHAR)
CREATE TABLE event (stadium_id VARCHAR)

What is the name of the stadium which held the most events?
SELECT t1.name FROM stadium AS t1 JOIN event AS t2 ON t1.id = t2.stadium_id GROUP BY t2.stadium_id ORDER BY COUNT(*) DESC LIMIT 1
SELECT "t1"."name" FROM "stadium" AS "t1" JOIN "event" AS "t2" ON "t1"."id" = "t2"."stadium_id" GROUP BY "t2"."stadium_id" ORDER BY COUNT(*) DESC NULLS LAST LIMIT 1