COMP 239 เป็นสิ่งจำเป็นสำหรับคลาสใด ?ไม่จำเป็นต้องใช้ตารางทั้งหมด
COMP 239 is a have-to for what classes ?It is not neccessary to use all the tables.
 ta:  campus_job_id [ int]  student_id [ int]  location [ varchar] 
SELECT DISTINCT COURSE_1.department, COURSE_1.name, COURSE_1.number FROM course AS COURSE_0, course AS COURSE_1, course_prerequisite WHERE COURSE_0.course_id = course_prerequisite.pre_course_id AND COURSE_0.department = 'COMP' AND COURSE_0.number = 239 AND COURSE_1.course_id = course_prerequisite.course_id