Find 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
subject ID refers to subject_id; subject name refers to subject_name; number of available courses for each subject refers to COUNT(*); joining of two tables (Courses and Subjects) on a common field (subject_id);