ManyToMany关系连接三个表，限制mysql中第三个表的第三个表限制的结果

Question

I have three tables that are in ManyToMany relationship. 1.playlist 2.tracks 3.playlist_tracks

I want to retrieve 10 playlist with limit of 5 songs. how can i do it? I have tried with this way..

select t1.id as playlistId, t2.playlist_id as pivot_playlist_id, t2.track_id as track_id 
from playlist t1 
join playlist_tracks t2 on t1.id = t2.playlist_id
left join (
    select t3.id as track_id , t3.is_published 
    from tracks t3
    where t3.is_published = 1 
    group by t3.id limit 5
    ) xx on t2.track_id = xx.track_id 
where t1.prior != 0 AND t1.is_published = 1 ;

but don't get proper result, as it is not applying limit on tracks. It returns all the songs of particular playlist. Where I am doing wrong> Please help me.Here is the DBfiddle for the same sqlfiddle.com/#!9/feddbd/1

Answer 1

Try this for limiting 5 songs for each playlist_track :

SET @playlist_id=-1;
SELECT * FROM
(
  SELECT track_id,
@row_number:=CASE
    WHEN @playlist_id= playlist_id THEN @row_number + 1
    ELSE 1
END AS track_number,
@playlist_id:=playlist_id as playlist_id
FROM playlist_tracks
ORDER BY playlist_id
) X WHERE track_number<=5