What are the names of all courses that have some students enrolled?
SELECT DISTINCT T1.course_name FROM Courses AS T1 JOIN Student_Enrolment_Courses AS T2 ON T1.course_id  =  T2.course_id
SELECT DISTINCT T1.course_name FROM Courses AS T1 JOIN Student_Enrolment_Courses AS T2 ON T1.course_id  =  T2.course_id
[{'course_name': 'la'}, {'course_name': 'pl'}, {'course_name': 'ai'}, {'course_name': 'math'}, {'course_name': 'ml'}, {'course_name': 'os'}, {'course_name': 'en'}, {'course_name': 'nlp'}, {'course_name': 'rs'}, {'course_name': 'db'}]