MySQL分组查询获取每个学生前n条分数记录(分组查询前n条记录)

CREATE TABLE `t_test` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `stuid` varchar(36) NOT NULL,
  `score` int(11) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=11 DEFAULT CHARSET=utf8;
INSERT INTO `testdb`.`t_test` (`id`, `stuid`, `score`) VALUES ('1', '111', '90');
INSERT INTO `testdb`.`t_test` (`id`, `stuid`, `score`) VALUES ('2', '111', '11');
INSERT INTO `testdb`.`t_test` (`id`, `stuid`, `score`) VALUES ('3', '111', '34');
INSERT INTO `testdb`.`t_test` (`id`, `stuid`, `score`) VALUES ('4', '111', '99');
INSERT INTO `testdb`.`t_test` (`id`, `stuid`, `score`) VALUES ('5', '222', '11');
INSERT INTO `testdb`.`t_test` (`id`, `stuid`, `score`) VALUES ('6', '222', '33');
INSERT INTO `testdb`.`t_test` (`id`, `stuid`, `score`) VALUES ('7', '222', '41');
INSERT INTO `testdb`.`t_test` (`id`, `stuid`, `score`) VALUES ('8', '333', '123');
INSERT INTO `testdb`.`t_test` (`id`, `stuid`, `score`) VALUES ('9', '333', '100');
INSERT INTO `testdb`.`t_test` (`id`, `stuid`, `score`) VALUES ('10', '333', '99');

测试数据

SELECT *,
(SELECT count(id) FROM t_test t2
where t1.stuid=t2.stuid AND 
t2.score>t1.score -- 获取t2大于t1的记录数
)as maxcnt
 from t_test t1

到这一步就很简单了.其实只要根据情况取macnt的数据就行了,如果要取前2条,那么筛选maxcnt<2的数据即可.

(如111学生大于99的有0条,大于90的有1条,大于34的有2条,那么要取最高分的前3条,就是maxcnt<3)

SELECT *
 FROM t_test t1
WHERE
(
SELECT count(id) FROM t_test t2
where t2.stuid=t1.stuid and t2.score>t1.score
)<3
ORDER BY stuid asc,score DESC

效果图