CREATE TABLE student (stuid NUMBER, lname CLOB, fname CLOB, age NUMBER, sex CLOB, major NUMBER, advisor NUMBER, city_code CLOB)
CREATE TABLE lives_in (stuid NUMBER, dormid NUMBER, room_number NUMBER)
CREATE TABLE dorm (dormid NUMBER, dorm_name CLOB, student_capacity NUMBER, gender CLOB)
CREATE TABLE has_amenity (dormid NUMBER, amenid NUMBER)
CREATE TABLE dorm_amenity (amenid NUMBER, amenity_name CLOB)

What is the last name of every student who is either female or living in a city with the code BAL or male and under 20?
SELECT lname FROM student WHERE sex = 'F' AND city_code = 'BAL' UNION SELECT lname FROM student WHERE sex = 'M' AND age < 20
SELECT "lname" FROM "student" WHERE "city_code" = 'BAL' AND "sex" = 'F' UNION SELECT "lname" FROM "student" WHERE "age" < 20 AND "sex" = 'M'