SQL随机4行与不同的列

Question

I have table representing music tracks with columns id, artist, name, src, sample_start and level. I want to select random 4 rows but with distinct artists and specified level. The closest I got was this, but it's not random as max id is selected.

'SELECT * FROM tracks WHERE level = :level AND id IN
 (SELECT max(id) FROM tracks GROUP BY artist)
 ORDER BY RAND() LIMIT 4'

Answer 1

你可以试试这个吗？

SELECT * FROM tracks WHERE LEVEL = :LEVEL AND id IN (SELECT DISTINCT id FROM tracks ORDER BY RAND()) ORDER BY RAND() LIMIT 4