Mysql相关问题收集

DROP TABLE IF EXISTS `sc`;
CREATE TABLE `sc` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(200) CHARACTER SET utf8 DEFAULT NULL,
  `class` varchar(200) CHARACTER SET utf8 DEFAULT NULL,
  `score` int(11) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=9 DEFAULT CHARSET=latin1;

 
insert into sc values (1,‘badkano‘,‘一年一班‘,100);
insert into sc values (2,‘百度知道团长‘,‘一年一班‘,99);
insert into sc values (3,‘du小短‘,‘一年一班‘,95);
insert into sc values (4,‘du小小动‘,‘一年一班‘,97);
insert into sc values (5,‘du小智‘,‘一年一班‘,80);
insert into sc values (6,‘吕布‘,‘一年二班‘,67);
insert into sc values (7,‘赵云‘,‘一年二班‘,90);
insert into sc values (8,‘典韦‘,‘一年二班‘,89);
insert into sc values (9,‘关羽‘,‘一年二班‘,70);
insert into sc values (10,‘马超‘,‘一年二班‘,98);

select 
    * 
from sc t
where 
    (select count(1)+1 from sc where class=t.class and score>t.score)
    <= 3