SELECT * FROM table_score ORDER BY score DESC;

SELECT *,

(SELECT count(DISTINCT score) FROM table_score AS b WHERE a.score<b.score)+1 AS rank, #获取排名，并列

(SELECT b.score FROM table_score AS b WHERE b.score>a.score ORDER BY b.score LIMIT 1)-a.score AS subtract #获取和上一名学生成绩的差 
FROM table_score AS a WHERE a.s_id = 13; #获取学生周一的成绩排名和与上一名的成绩差

SELECT *,

(SELECT count(DISTINCT score) FROM table_score AS b WHERE a.score<b.score)+1 AS rank #获取排名-并列

FROM table_score AS a ORDER BY rank; #获取学生成绩排名

SELECT a.*,

(@rowNum:=@rowNum+1) AS rank #计算行号 
FROM table_score AS a,

(SELECT (@rowNum :=0) ) b

ORDER BY a.score DESC;