How many releases by the artist michael jackson are tagged "pop"?
tag = 'pop';
SELECT COUNT(T1.groupName) FROM torrents AS T1 INNER JOIN tags AS T2 ON T1.id = T2.id WHERE T2.tag = 'pop' AND T1.artist = 'michael jackson'
database name:db_id music_tracker
torrents table torrents Cols: groupName dtype text, totalSnatched dtype integer, artist dtype text, groupYear dtype integer, releaseType dtype text, groupId dtype integer, id dtype integer, 
tags table tags Cols: index dtype integer, id dtype integer, tag dtype text, 
