DELETE FROM courses WHERE id_course = 'course134';
DELETE FROM courses WHERE id_course = 'course143';
DELETE FROM courses WHERE id_course = 'course79';
DELETE FROM courses WHERE id_course = 'course89';
DELETE FROM courses WHERE id_course = 'course51';
DELETE FROM courses WHERE id_course = 'course166';
DELETE FROM courses WHERE id_course = 'course38';
DELETE FROM courses WHERE id_course = 'course80';
DELETE FROM courses WHERE id_course = 'course144';
DELETE FROM courses WHERE id_course = 'course147';
