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

Show all cities where students live.
SELECT DISTINCT city_code FROM student
SELECT DISTINCT "city_code" FROM "student"