CREATE TABLE has_allergy (stuid NUMBER, allergy CLOB)
CREATE TABLE student (stuid NUMBER, lname CLOB, fname CLOB, age NUMBER, sex CLOB, major NUMBER, advisor NUMBER, city_code CLOB)
CREATE TABLE allergy_type (allergy CLOB, allergytype CLOB)

Which advisor has most number of students?
SELECT advisor FROM student GROUP BY advisor ORDER BY COUNT(*) DESC LIMIT 1
SELECT "advisor" FROM "student" GROUP BY "advisor" ORDER BY COUNT(*) DESC FETCH FIRST 1 ROWS ONLY