如果每个用户的mysql选择计数大于3

Question

I have the following mysql table (the real table is actually very huge, about 2 million rows):

----------------------------
userId | artistId | trackId
----------------------------
user1  | artist1  | track1
-------|----------|--------
user1  | artist1  | track1
-------|----------|--------
user1  | artist1  | track1
-------|----------|--------
user2  | artist1  | track1
-------|----------|--------
user2  | artist2  | track2
-------|----------|--------
user2  | artist2  | track2
-------|----------|--------
 ....  |   ....   |  ....

What I would like to is: for each user, select artists that users listened more than 3 different tracks of them (ie, 3 tracks of the same artist). This is because I need to consider this selection as users preferences on artists, so if eg, a user listened only to 1 or two tracks of an artist, I don't want to consider it as "preferences/likes". Here is the query that I wrote but I am not sure if this is correct:

select p.userId, p.artistId, p.trackId 
from lastfm_part2 p 
join 
(select userId, artistId, trackId 
from lastfm_part2 
group by userId, artistId, trackId 
having count(trackId) > 3) as m 
on m.userId = p.userId and m.artistId = p.artistId and p.trackID = m.trackId

PS. I need to return all the rows, even though they may seem to be duplicates (same user, same track, same artist), but in reality they are related to different time stamps. I appreciate if someone help me understand if this query is correct.

Thanks

Answer 1

I tested it in Oracle so maybe MySQL is a little different but the next query did work for me.

SELECT p.userId, p.artistId, COUNT( DISTINCT p.trackId )
FROM lastfm_part2
group by userId, artistId
having count( DISTINCT p.trackId ) > 3;