业务场景:
从成绩表中,查询每门课程的top2的学生的所有信息
建表语句:
CREATE TABLE `subject` (
`Id` int(11) NOT NULL DEFAULT '0',
`subject_name` varchar(200) DEFAULT NULL,
`sname` varchar(255) DEFAULT NULL,
`score` int(11) DEFAULT NULL,
PRIMARY KEY (`Id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8
插入记录:
INSERT INTO subject VALUES(1,'语文','张三',85);
INSERT INTO subject VALUES(2,'语文','李四',72);
INSERT INTO subject VALUES(3,'语文','王五',96);
INSERT INTO subject VALUES(4,'语文','赵六',78);
INSERT INTO subject VALUES(5,'语文','刘七',81);
INSERT INTO subject VALUES(6,'数学','张三',82);
INSERT INTO subject VALUES(7,'数学','李四',99);
INSERT INTO subject VALUES(8,'数学','王五',70);
INSERT INTO subject VALUES(9,'数学','赵六',91);
INSERT INTO subject VALUES(10,'数学','刘七',78);
INSERT INTO subject VALUES(11,'英语','张三',62);
INSERT INTO subject VALUES(12,'英语','李四',93);
INSERT INTO subject VALUES(13,'英语','王五',98);
INSERT INTO subject VALUES(14,'英语','赵六',70);
INSERT INTO subject VALUES(15,'英语','刘七',52);
查询前两名sql:
mysql不支持row_number
SELECT a.*
FROM subject a
WHERE (
SELECT COUNT(1)
FROM subject b
WHERE a.`subject_name` = b.`subject_name`
AND b.`score` > a.score
) <2
ORDER BY subject_name, score DESC;
本文地址:https://blog.csdn.net/weixin_42123844/article/details/107640844
如对本文有疑问, 点击进行留言回复!!
JWT RS256加解密、JWK获取PublicKey和PrivateKey、从已存在公私钥加解密JWT
pytorch安装实录(win10+cuda8+pycharm+anaconda)
小练习题(69)有n个人围成一圈,顺序排号。从第一个人开始报数(从1到3报数),凡报到3的人退出圈子,问最后留下的是原来第几号的那位
两种方法 更改jupyter notebook的打开路径/默认工作路径
RobotFramework接口自动化-全局变量解决保持登录问题
网友评论