用mysql查询各班前3名成绩

CREATE TABLE sc

 

(

 

  id    INT,

 

  name  VARCHAR(20),

 

  class VARCHAR(20),

 

  score INT

 

);

 

 

 

INSERT INTO sc VALUES (11, 'zx', '一年1班', 68);

 

INSERT INTO sc VALUES (12, 'zx1', '一年1班', 98);

 

INSERT INTO sc VALUES (13, 'zx2', '一年1班', 58);

 

INSERT INTO sc VALUES (14, 'zx3', '一年1班', 48);

 

INSERT INTO sc VALUES (15, 'zx4', '一年2班', 88);

 

INSERT INTO sc VALUES (16, 'zx5', '一年2班', 68);

 

INSERT INTO sc VALUES (17, 'zx6', '一年2班', 98);

 

INSERT INTO sc VALUES (18, 'zx7', '一年3班', 78);

 

INSERT INTO sc VALUES (19, 'zx8', '一年2班', 58);

 

INSERT INTO sc VALUES (20, 'zx9', '一年1班', 88);

 

INSERT INTO sc VALUES (21, 'zx10', '一年3班', 83);

 

INSERT INTO sc VALUES (22, 'zx11', '一年3班', 82);

 

INSERT INTO sc VALUES (23, 'zx12', '一年3班', 81);

 

 

 

SELECT

 

  s1.name,

 

  s1.class,

 

  s1.score

 

FROM sc s1

 

WHERE

 

  (

 

    SELECT count(1)

 

    FROM sc s2

 

    WHERE

 

      s1.class = s2.class AND s2.score >= s1.score

 

  ) <= 3

 

ORDER BY s1.class, s1.score DESC;

优化：使用存储过程或函数来分批查询