Tell me the courses that belong to the subject named "Computer Science".
select t1.course_name from courses as t1 join subjects as t2 on t1.subject_id = t2.subject_id where t2.subject_name = "Computer Science"
Tell me the courses that belong to the subject named "Arts".
select t1.course_name from courses as t1 join subjects as t2 on t1.subject_id = t2.subject_id where t2.subject_name = "Arts"
Tell me the subject ID, subject name, and the corresponding number of available courses for each subject.
select t1.subject_id, t2.subject_name, count(*) from courses as t1 join subjects as t2 on t1.subject_id = t2.subject_id group by t1.subject_id