What are the instructors name for each of those ids the are advising more than one student?
SELECT T1.name FROM instructor AS T1 JOIN advisor AS T2 ON T1.id   =   T2.i_id GROUP BY T2.i_id HAVING count ( * )   >  1
instructors advising more than one student refers to HAVING COUNT(*) > 1; instructor's name refers to SELECT T1.name;