CREATE TABLE student (lname VARCHAR2, sex VARCHAR2, city_code VARCHAR2, age VARCHAR2)

Find the last name of students who is either female (sex is F) and living in the city of code BAL or male (sex is M) and in age of below 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'