sql统计－关于学生成绩
学生成绩表(stuscore)：
| 姓名：name |
课程：subject |
分数：score |
学号：stuid |
| 张三 |
数学 |
89 |
1 |
| 张三 |
语文 |
80 |
1 |
| 张三 |
英语 |
70 |
1 |
| 李四 |
数学 |
90 |
2 |
| 李四 |
语文 |
70 |
2 |
| 李四 |
英语 |
80 |
2 |
创建表
SET ANSI_NULLS ONGOSET QUOTED_IDENTIFIER ONGOSET ANSI_PADDING ONGOCREATE TABLE [dbo].[stuscore]( [name] [varchar](50) COLLATE Chinese_PRC_CI_AS NULL, [subject] [varchar](50) COLLATE Chinese_PRC_CI_AS NULL, [score] [int] NULL, [stuid] [int] NULL) ON [PRIMARY] GOSET ANSI_PADDING OFF
问题：
1. 计算每个人的总成绩并排名(要求显示字段：姓名，总成绩)
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)
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)
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）
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)
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)
7. 统计如下：
| 学号 |
姓名 |
语文 |
数学 |
英语 |
总分 |
平均分 |
|
|
|
|
|
|
|
|
8．列出各门课程的平均成绩（要求显示字段：课程，平均成绩）
9．列出数学成绩的排名（要求显示字段：学号，姓名，成绩，排名）
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）
11．求出李四的数学成绩的排名
12．统计如下：
| 课程 |
不及格（0-59）个 |
良（60-80）个 |
优（81-100）个 |
|
|
|
|
|
13．统计如下：数学:张三(50分),李四(90分),王五(90分),赵六(76分)
答案：
1. 计算每个人的总成绩并排名
select
name,
sum
(score)
as
allscore
from
stuscore
group
by
name
order
by
allscore
2. 计算每个人的总成绩并排名
select
distinct
t1.name,t1.stuid,t2.allscore
from
stuscore t1,(
select
stuid,
sum
(score)
as
allscore
from
stuscore
group
by
stuid)t2
where
t1.stuid
=
t2.stuid
order
by
t2.allscore
desc
3. 计算每个人单科的最高成绩
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
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
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
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
7.学号 姓名 语文 数学 英语 总分 平均分
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
select
subject,
avg
(score)
as
avgscore
from
stuscore
group
by
subject
9.列出数学成绩的排名
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
select
DENSE_RANK ()
OVER
(
order
by
score
desc
)
as
row,name,subject,score,stuid
from
stuscore
where
subject
=
'
数学
'
order
by
score
desc
declare
@tmp
table
(pm
int
identity
(
1
,
1
),name
varchar
(
50
),score
int
,stuid
int
)
insert
into
@tmp
select
name,score,stuid
from
stuscore
where
subject
=
'
数学
'
order
by
score
desc
select
*
from
@tmp
10. 列出数学成绩在2-3名的学生
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
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. 课程 不及格（ -59 ） 良（ -80 ） 优（ -100 ）
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
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