Question: Find the name of the person who has no student friends.
Schema: create table person (name varchar, job varchar, PRIMARY KEY (name)); create table personfriend (name varchar, friend varchar, PRIMARY KEY (name)); create table person (name varchar, PRIMARY KEY (name))
SQL: select name from person except select t2.name from person as t1 join personfriend as t2 on t1.name = t2.friend where t1.job = 'student'