SELECT course_id FROM student_course_registrations WHERE student_id = 121 UNION SELECT course_id FROM student_course_attendance WHERE student_id = 121
What are the ids of the courses that are registered or attended by the student whose id is 121?
SELECT course_id FROM student_course_registrations WHERE student_id = 121 UNION SELECT course_id FROM student_course_attendance WHERE student_id = 121
select course_id from student_course_registrations where student_id = value union select course_id from student_course_attendance where student_id = value
What are the ids of the courses that are registered or attended by the student whose id is 121 ?