CREATE TABLE dorm_amenity (amenid NUMBER, amenity_name CLOB)
CREATE TABLE lives_in (stuid NUMBER, dormid NUMBER, room_number NUMBER)
CREATE TABLE dorm (dormid NUMBER, dorm_name CLOB, student_capacity NUMBER, gender CLOB)
CREATE TABLE has_amenity (dormid NUMBER, amenid NUMBER)
CREATE TABLE student (stuid NUMBER, lname CLOB, fname CLOB, age NUMBER, sex CLOB, major NUMBER, advisor NUMBER, city_code CLOB)

Find the name of amenity that is most common in all dorms.
SELECT T1.amenity_name FROM dorm_amenity AS T1 JOIN has_amenity AS T2 ON T1.amenid = T2.amenid GROUP BY T2.amenid ORDER BY COUNT(*) DESC LIMIT 1
SELECT "T1"."amenity_name" FROM "dorm_amenity" "T1" JOIN "has_amenity" "T2" ON "T1"."amenid" = "T2"."amenid" GROUP BY "T2"."amenid" ORDER BY COUNT(*) DESC FETCH FIRST 1 ROWS ONLY