1.在分析问题前，我们先把数据准备好。

CREATE TABLE student(
name 		VARCHAR(10),
subject		VARCHAR(10),
score		INT(10)
);

2.插入数据

INSERT INTO student VALUES
("张三","java",71),
("李四","java",82),
("王五","java",90),
("赵六","java",98),
("孙七","java",90),
("张三","python",81),
("李四","python",92),
("王五","python",93),
("赵六","python",97),
("孙七","python",70);

思路

查询各科成绩前三名，前三名都有一个特点，比他们成绩高的人数小于3，成绩就是前三名。

SELECT		T1.*
FROM 		student T1
LEFT JOIN	(SELECT DISTINCT subject, score FROM student) T2
ON 			T1.subject = T2.subject
AND 		T1.score < T2.score
GROUP BY 	name,subject,score
HAVING		COUNT(1) < 3
ORDER BY 	subject,score DESC