Table schema:
CREATE TABLE dorm_amenity (amenity_name VARCHAR, amenid VARCHAR); CREATE TABLE has_amenity (amenid VARCHAR)

Question: Find the name of amenity that is most common in all dorms.
SQL: 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