Hello there!  Can you tell me, which media type is the least common associated with all tracks?
SELECT T1.Name FROM MEDIATYPE AS T1 JOIN TRACK AS T2 ON T1.MediaTypeId   =   T2.MediaTypeId GROUP BY T2.MediaTypeId ORDER BY COUNT ( * )  ASC LIMIT 1
least common media type associated with all tracks refers to MIN(COUNT(*)) for each media type;