SELECT min(grade) FROM Highschooler WHERE id NOT IN (SELECT T1.student_id FROM Friend AS T1 JOIN Highschooler AS T2 ON T1.student_id  =  T2.id)
Find the minimum grade of students who have no friends.
SELECT min ( grade ) FROM Highschooler WHERE id NOT IN ( SELECT T1.student_id FROM Friend AS T1 JOIN Highschooler AS T2 ON T1.student_id = T2.id )
select min ( grade ) from highschooler where id not in ( select t1 . student_id from friend as t1 join highschooler as t2 on t1 . student_id = t2 . id )
Find the minimum grade of students who have no friends .