วันศุกร์คลาส MCDB ใดไม่พบกัน ?ไม่จำเป็นต้องใช้ทุกตาราง
Which MCDB classes don 't meet on Friday ?It is not neccessary to use all the tables.
 program_requirement:  program_id [ int]  category [ varchar]  min_credit [ int]  additional_req [ varchar] 
SELECT DISTINCT course.department, course.name, course.number FROM course INNER JOIN course_offering ON course.course_id = course_offering.course_id INNER JOIN semester ON semester.semester_id = course_offering.semester WHERE course_offering.friday = 'N' AND course.department = 'MCDB' AND semester.semester = 'WN' AND semester.year = 2016