query: SELECT course_id FROM course EXCEPT SELECT course_id FROM prereq
question: Find the id of the courses that do not have no prerequisite?
query_toks: SELECT course_id FROM course EXCEPT SELECT course_id FROM prereq
query_toks_no_value: select course_id from course except select course_id from prereq
question_toks: Find the id of the courses that do not have no prerequisite?