Mysql相关

我有个同学最近在学Mysql数据库，为了测试自己的学习成果，他们老大出了6道Mysql试题让他去做，晚上回来他又分享给我，我感觉非常经典，记录了这几道试题已及答案。

将测试数据表导入数据库，其中name字段代表“姓名”，score字段代表“分数”。

create table `t1` (     `id` double ,     `name` varchar (300),     `score` double  );

insert into `t1` (`id`, `name`, `score`) values('1','n1','59'); insert into `t1` (`id`, `name`, `score`) values('2','n2','66'); insert into `t1` (`id`, `name`, `score`) values('3','n3','78'); insert into `t1` (`id`, `name`, `score`) values('4','n1','48'); insert into `t1` (`id`, `name`, `score`) values('5','n3','85'); insert into `t1` (`id`, `name`, `score`) values('6','n5','51'); insert into `t1` (`id`, `name`, `score`) values('7','n4','98'); insert into `t1` (`id`, `name`, `score`) values('8','n5','53'); insert into `t1` (`id`, `name`, `score`) values('9','n2','67'); insert into `t1` (`id`, `name`, `score`) values('10','n4','88'); 1. 单分数最高的人和单分数最低的人。 mysql> select name,max(score) from t1; 2. 两门分数加起来的第2至5名。 mysql> select name,sum(score) from t1 group by name order by sum(score) desc limit 1,4; +------+------------+ | name | sum(score) | +------+------------+ | n3   |        163 |  | n2   |        133 |  | n1   |        107 |  | n5   |        104 |  +------+------------+ 3. 两门总分数在150分以下的人。 select name sum(score) from t1 group by name having sum(score) < 150; 4. 两门平均分数介于60和80的人。 select name,avg(score) from t1 group by name having avg(score) between 60 and 80; select name,avg(score) from t1 group by name having ave(score) >60 and avg(score) <80; 5. 总分大于150分，平均分小于90分的人数。 mysql> select name,sum(score),avg(score) from t1 group by name having sum(score)>150 and avg(score)<90; +------+------------+------------+ | name | sum(score) | avg(score) | +------+------------+------------+ | n3   |        163 |       81.5 |  +------+------------+------------+ 1 row in set (0.00 sec) 6. 总分大于150分，平均分小于90分的人数有几个。 select count(distinct name) from t1 group by name having sum(score) > 150 and avg(score) < 90;