首先，创建用到的数据表。
复制代码 代码示例:
CREATE TABLE `stuscore` (
`id` int(11) NOT NULL auto_increment,
`name` varchar(20) default NULL,
`subject` varchar(20) default NULL,
`score` varchar(20) default NULL,
`stuid` varchar(10) default NULL,
PRIMARY KEY (`id`)
) ENGINE=
innodb DEFAULT CHARSET=utf8;
然后，添加测试数据。
复制代码 代码示例:
/*Data for the table `stuscore` */
insert into `stuscore`(`id`,`name`,`subject`,`score`,`stuid`) values
(1,'张三','数学','89','1'),
(2,'张三','语文','80','1'),
(3,'张三','英语','70','1'),
(4,'李四','数学','90','2'),
(5,'李四','语文','70','2'),
(6,'李四','英语','80','2');
#--问题及解答：
1. 计算每个人的总成绩并排名（要求显示字段：姓名，总成绩）
复制代码 代码示例:
select name,sum(score) as allscore from stuscore group by name order by allscore desc
2. 计算每个人的总成绩并排名（要求显示字段: 学号，姓名，总成绩）
复制代码 代码示例:
select stuid,name,sum(score) as allscore from stuscore group by name order by allscore desc
3. 计算每个人单科的最高成绩(要求显示字段: 学号，姓名，课程，最高成绩)
复制代码 代码示例:
SELECT t1.stuid,t1.name,t1.subject,t1.score from stuscore t1,
(SELECT stuid,max(score) as maxscore from stuscore group by stuid) t2
where t1.stuid=t2.stuid and t1.score=t2.maxscore
4. 计算每个人的平均成绩（要求显示字段: 学号，姓名，平均成绩）
复制代码 代码示例:
select distinct t1.stuid,t1.name,t2.avgscore from stuscore t1,
(select stuid,avg(score) as avgscore from stuscore group by stuid) t2
where t1.stuid=t2.stuid
5. 列出各门课程成绩最好的学生(要求显示字段: 学号，姓名,科目，成绩)
复制代码 代码示例:
select t1.stuid,t1.name,t1.subject,t2.maxscore from stuscore t1,
(select subject,max(score) as maxscore from stuscore group by subject) t2
where t1.subject=t2.subject and t1.score=t2.maxscore
6. 列出各门课程成绩最好的两位学生(要求显示字段: 学号，姓名,科目，成绩)
复制代码 代码示例:
select distinct t1.* from stuscore t1 where t1.stuid in
(select top 2 stuscore.stuid from stuscore where subject = t1.subject order by score desc)
order by t1.subject
该语句未测试，目前知道在mysql下无法运行。mysql不支持select top。
7.
复制代码 代码示例:
select stuid as 学号,name as 姓名,
sum(case when subject='语文' then score else 0 end) as 语文,
sum(case when subject='数学' then score else 0 end) as 数学,
sum(case when subject='英语' then score else 0 end) as 英语,
sum(score) as 总分,(sum(score)/count(*)) as 平均分
from stuscore
group by stuid,name
order by 总分 desc
8. 列出各门课程的平均成绩（要求显示字段：课程，平均成绩）
select subject,avg(score) as avgscore from stuscore group by subject
9. 列出数学成绩的排名（要求显示字段：学号，姓名，成绩，排名）
复制代码 代码示例:
select * from stuscore where subject ='数学' order by score desc
不知道我自己想法对不对？
10. 列出数学成绩在2-3名的学生（要求显示字段：学号，姓名,科目，成绩）
复制代码 代码示例:
select t3.* from(
select top 2 t2.* from (
select top 3 name,subject,score,stuid from stuscore where subject='数学'
order by score desc
) t2 order by t2.score
) t3 order by t3.score desc
11. 求出李四的数学成绩的排名
复制代码 代码示例:
declare @tmp table(pm int,name varchar(50),score int,stuid int)
insert into @tmp select null,name,score,stuid from stuscore where subject='数学' order by score desc
declare @id int
set @id=0;
update @tmp set @id=@id+1,pm=@id
select * from @tmp where name='李四'
12.
复制代码 代码示例:
select subject,
(select count(*) from stuscore where score<60 and subject=t1.subject) as 不及格,
(select count(*) from stuscore where score between 60 and 80 and subject=t1.subject) as 良,
(select count(*) from stuscore where score >80 and subject=t1.subject) as 优
from stuscore t1 group by subject
13．统计如下：数学:张三(50分),李四(90分),王五(90分),赵六(76分)
复制代码 代码示例:
declare @s varchar(1000)
set @s=''
select @s =@s+','+name+'('+convert(varchar(10),score)+'分)' from stuscore where subject='数学'
set @s=stuff(@s,1,1,'')
print '数学:'+@s
说：第10，11，13题未验证，大家在使用时，注意测试。
