Table schema:
CREATE TABLE enroll (stu_num VARCHAR, enroll_grade VARCHAR, class_code VARCHAR); CREATE TABLE student (stu_lname VARCHAR, stu_num VARCHAR)

Question: What is the last name of the student who got a grade A in the class with code 10018.
SQL: SELECT T1.stu_lname FROM student AS T1 JOIN enroll AS T2 ON T1.stu_num = T2.stu_num WHERE T2.enroll_grade = 'A' AND T2.class_code = 10018