mysql 取出每科成绩前两名

只有一张表，自关联 ，比较分数，取前两名

SELECT * FROM stuscore A
WHERE
(SELECT COUNT(DISTINCT score) FROM stuscore B WHERE A.subject = B.subject AND B.score>=A.score)<=2
ORDER BY A.score DESC;

如果成绩相同的第二名有两个会都展示出来