Question: List the distinct hometowns that are not associated with any gymnast.
Schema: create table gymnast (gymnast_id varchar, PRIMARY KEY (gymnast_id)); create table people (hometown varchar, people_id varchar, PRIMARY KEY (hometown)); create table people (hometown varchar, PRIMARY KEY (hometown))
SQL: select distinct hometown from people except select distinct t2.hometown from gymnast as t1 join people as t2 on t1.gymnast_id = t2.people_id