sql语句练习

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sql语句练习

Student(S#,Sname,Sage,Ssex) 学生表 
Course(C#,Cname,T#) 课程表 
SC(S#,C#,score) 成绩表 
Teacher(T#,Tname) 教师表 问题： 
1、查询“001”课程比“002”课程成绩高的所有学生的学号； 
select a.S# from (select s#,score from
SC where C#='001') a,(select s#,score 
from SC where C#='002') b 
where a.score>b.score and a.s#=b.s#; 
2、查询平均成绩大于60分的同学的学号和平均成绩； 
 select S#,avg(score) 
 from sc 
 group by S# having avg(score) >60; 
3、查询所有同学的学号、姓名、选课数、总成绩； 
select
Student.S#,Student.Sname,count(SC.C#),sum(score) 
from Student left Outer join SC on
Student.S#=SC.S# 
group by Student.S#,Sname 
4、查询姓“李”的老师的个数； 
select count(distinct(Tname)) 
from Teacher 
where Tname like '李%'; 
5、查询没学过“叶平”老师课的同学的学号、姓名； 
 select Student.S#,Student.Sname 
 from Student 
 where S# not in (select distinct(
SC.S#) from SC,Course,Teacher where
SC.C#=Course.C# and Teacher.T#=Course.T# and Teacher.Tname='叶平'); 
6、查询学过“001”并且也学过编号“002”课程的同学的学号、姓名； 
select Student.S#,Student.Sname from
Student,SC where Student.S#=SC.S# and SC.C#='001'and exists( Select * from SC
as SC_2 where SC_2.S#=SC.S# and SC_2.C#='002'); 
7、查询学过“叶平”老师所教的所有课的同学的学号、姓名； 
select S#,Sname 
from Student 
where S# in (select S# from SC ,Course
,Teacher where SC.C#=Course.C# and Teacher.T#=Course.T# and Teacher.Tname='叶平' group by S# having count(SC.C#)=(select count(C#) from
Course,Teacher where
Teacher.T#=Course.T# and Tname='叶平')); 
8、查询课程编号“002”的成绩比课程编号“001”课程低的所有同学的学号、姓名； 
Select S#,Sname from (select
Student.S#,Student.Sname,score ,(select score from SC SC_2 where
SC_2.S#=Student.S# and SC_2.C#='002') score2 
from Student,SC where Student.S#=SC.S#
and C#='001') S_2 where score2 <score; 
9、查询所有课程成绩小于60分的同学的学号、姓名； 
select S#,Sname 
from Student 
where S# not in (select Student.S# from
Student,SC where S.S#=SC.S# and score>60); 
10、查询没有学全所有课的同学的学号、姓名； 
 select Student.S#,Student.Sname 
 from Student,SC 
 where Student.S#=SC.S# group by Student.S#,Student.Sname having count(C#)
<(select count(C#) from Course); 
11、查询至少有一门课与学号为“1001”的同学所学相同的同学的学号和姓名； 
 select S#,Sname from Student,SC where
Student.S#=SC.S# and C# in select C# from SC where S#='1001'; 
12、查询至少学过学号为“001”同学所有一门课的其他同学学号和姓名； 
 select distinct SC.S#,Sname 
 from Student,SC 
 where Student.S#=SC.S# and C# in
(select C# from SC where S#='001'); 
13、把“SC”表中“叶平”老师教的课的成绩都更改为此课程的平均成绩； 
 update SC set score=(select
avg(SC_2.score) 
 from SC SC_2 
 where SC_2.C#=SC.C# ) from
Course,Teacher where Course.C#=SC.C# and Course.T#=Teacher.T# and
Teacher.Tname='叶平'); 
14、查询和“1002”号的同学学习的课程完全相同的其他同学学号和姓名； 
 select S# from SC where C# in (select
C# from SC where S#='1002') 
 group by S# having count(*)=(select
count(*) from SC where S#='1002'); 
15、删除学习“叶平”老师课的SC表记录； 
 Delect SC 
 from course ,Teacher 
 where Course.C#=SC.C# and Course.T#=
Teacher.T# and Tname='叶平'; 
16、向SC表中插入一些记录，这些记录要求符合以下条件：没有上过编号“003”课程的同学学号、2、 
 号课的平均成绩； 
 Insert SC select S#,'002',(Select
avg(score) 
 from SC where C#='002') from Student
where S# not in (Select S# from SC where C#='002'); 
17、按平均成绩从高到低显示所有学生的“数据库”、“企业管理”、“英语”三门的课程成绩，按如下形式显示：学生ID,,数据库,企业管理,英语,有效课程数,有效平均分 
 SELECT S# as 学生ID 
 ,(SELECT score FROM SC WHERE
SC.S#=t.S# AND C#='004') AS 数据库 
 ,(SELECT score FROM SC WHERE
SC.S#=t.S# AND C#='001') AS 企业管理 
 ,(SELECT score FROM SC WHERE
SC.S#=t.S# AND C#='006') AS 英语 
 ,COUNT(*) AS 有效课程数, AVG(t.score) AS 平均成绩 
 FROM SC AS t 
 GROUP BY S# 
 ORDER BY avg(t.score) 
18、查询各科成绩最高和最低的分：以如下形式显示：课程ID，最高分，最低分 
 SELECT L.C# As 课程ID,L.score AS 最高分,R.score AS 最低分 
 FROM SC L ,SC AS R 
 WHERE L.C# = R.C# and 
 L.score = (SELECT MAX(IL.score) 
 FROM SC AS
IL,Student AS IM 
 WHERE L.C# = IL.C#
and IM.S#=IL.S# 
 GROUP BY IL.C#) 
 AND 
 R.Score = (SELECT MIN(IR.score) 
 FROM SC AS IR 
 WHERE R.C# = IR.C# 
 GROUP BY IR.C# 
 ); 
19、按各科平均成绩从低到高和及格率的百分数从高到低顺序 
 SELECT t.C# AS 课程号,max(course.Cname)AS 课程名,isnull(AVG(score),0)
AS 平均成绩 
 ,100 * SUM(CASE WHEN isnull(score,0)>=60 THEN 1 ELSE 0 END)/COUNT(*)
AS 及格百分数 
 FROM SC T,Course 
 where t.C#=course.C# 
 GROUP BY t.C# 
 ORDER BY 100 * SUM(CASE WHEN isnull(score,0)>=60 THEN 1 ELSE 0
END)/COUNT(*) DESC 
20、查询如下课程平均成绩和及格率的百分数(用"1行"显示): 企业管理（001），马克2思（002），OO&UML （003），数据库（004） 
 SELECT SUM(CASE WHEN C# ='001' THEN
score ELSE 0 END)/SUM(CASE C# WHEN '001' THEN 1 ELSE 0 END) AS 企业管理平均分 
 ,100 * SUM(CASE WHEN C# = '001'
AND score >= 60 THEN 1 ELSE 0 END)/SUM(CASE WHEN C# = '001' THEN 1 ELSE 0
END) AS 企业管理及格百分数 
 ,SUM(CASE WHEN C# = '002' THEN
score ELSE 0 END)/SUM(CASE C# WHEN '002' THEN 1 ELSE 0 END) AS 马克2思平均分 
 ,100 * SUM(CASE WHEN C# = '002'
AND score >= 60 THEN 1 ELSE 0 END)/SUM(CASE WHEN C# = '002' THEN 1 ELSE 0
END) AS 马克2思及格百分数 
 ,SUM(CASE WHEN C# = '003' THEN
score ELSE 0 END)/SUM(CASE C# WHEN '003' THEN 1 ELSE 0 END) AS UML平均分 
 ,100 * SUM(CASE WHEN C# = '003'
AND score >= 60 THEN 1 ELSE 0 END)/SUM(CASE WHEN C# = '003' THEN 1 ELSE 0
END) AS UML及格百分数 
 ,SUM(CASE WHEN C# = '004' THEN
score ELSE 0 END)/SUM(CASE C# WHEN '004' THEN 1 ELSE 0 END) AS 数据库平均分 
 ,100 * SUM(CASE WHEN C# = '004'
AND score >= 60 THEN 1 ELSE 0 END)/SUM(CASE WHEN C# = '004' THEN 1 ELSE 0
END) AS 数据库及格百分数 
FROM SC 
21、查询不同老师所教不同课程平均分从高到低显示 
SELECT max(Z.T#) AS 教师ID,MAX(Z.Tname) AS 教师姓名,C.C# AS 课程ＩＤ,MAX(C.Cname) AS 课程名称,AVG(Score) AS 平均成绩 
 FROM SC AS T,Course AS C ,Teacher AS
Z 
 where T.C#=C.C# and C.T#=Z.T# 
GROUP BY C.C# 
ORDER BY AVG(Score) DESC 
22、查询如下课程成绩第 3 名到第 6 名的学生成绩单：企业管理（001），马克2思（002），UML （003），数据库（004） 
 [学生ID],[学生姓名],企业管理,马克2思,UML,数据库,平均成绩 
 SELECT DISTINCT top 3 
 SC.S# As 学生学号, 
 Student.Sname AS 学生姓名 , 
 T1.score AS 企业管理, 
 T2.score AS 马克2思, 
 T3.score AS UML, 
 T4.score AS 数据库, 
 ISNULL(T1.score,0) +
ISNULL(T2.score,0) + ISNULL(T3.score,0) + ISNULL(T4.score,0) as 总分 
 FROM Student,SC LEFT JOIN SC AS T1 
 ON SC.S# = T1.S#
AND T1.C# = '001' 
 LEFT JOIN SC AS T2 
 ON SC.S# = T2.S#
AND T2.C# = '002' 
 LEFT JOIN SC AS T3 
 ON SC.S# = T3.S#
AND T3.C# = '003' 
 LEFT JOIN SC AS T4 
 ON SC.S# = T4.S#
AND T4.C# = '004' 
 WHERE student.S#=SC.S# and 
 ISNULL(T1.score,0) +
ISNULL(T2.score,0) + ISNULL(T3.score,0) + ISNULL(T4.score,0) 
 NOT IN 
 (SELECT 
 DISTINCT 
 TOP 15 WITH TIES 
 ISNULL(T1.score,0) +
ISNULL(T2.score,0) + ISNULL(T3.score,0) + ISNULL(T4.score,0) 
 FROM sc 
 LEFT JOIN sc AS T1 
 ON sc.S# = T1.S# AND T1.C# = 'k1' 
 LEFT JOIN sc AS T2 
 ON sc.S# = T2.S#
AND T2.C# = 'k2' 
 LEFT JOIN sc AS T3 
 ON sc.S# = T3.S#
AND T3.C# = 'k3' 
 LEFT JOIN sc AS T4 
 ON sc.S# = T4.S# AND T4.C# = 'k4' 
 ORDER BY ISNULL(T1.score,0) +
ISNULL(T2.score,0) + ISNULL(T3.score,0) + ISNULL(T4.score,0) DESC); 
23、统计列印各科成绩,各分数段人数:课程ID,课程名称,[100-85],[85-70],[70-60],[ <60] 
 SELECT SC.C# as 课程ID, Cname as 课程名称 
 ,SUM(CASE WHEN score BETWEEN 85
AND 100 THEN 1 ELSE 0 END) AS [100 - 85] 
 ,SUM(CASE WHEN score BETWEEN 70
AND 85 THEN 1 ELSE 0 END) AS [85 - 70] 
 ,SUM(CASE WHEN score BETWEEN 60
AND 70 THEN 1 ELSE 0 END) AS [70 - 60] 
 ,SUM(CASE WHEN score < 60 THEN
1 ELSE 0 END) AS [60 -] 
 FROM SC,Course 
 where SC.C#=Course.C# 
 GROUP BY SC.C#,Cname; 
24、查询学生平均成绩及其名次 
 SELECT 1+(SELECT COUNT( distinct 平均成绩) 
 FROM (SELECT S#,AVG(score)
AS 平均成绩 
 FROM SC 
 GROUP BY S# 
 ) AS T1 
 WHERE 平均成绩 > T2.平均成绩) as 名次, 
 S# as 学生学号,平均成绩 
 FROM (SELECT S#,AVG(score) 平均成绩 
 FROM SC 
 GROUP BY S# 
 ) AS T2 
 ORDER BY 平均成绩
desc; 
 
25、查询各科成绩前三名的记录:(不考虑成绩并列情况) 
 SELECT t1.S# as 学生ID,t1.C# as 课程ID,Score as 分数 
 FROM SC t1 
 WHERE score IN (SELECT TOP 3 score 
 FROM SC 
 WHERE t1.C#= C# 
 ORDER BY score DESC 
 ) 
 ORDER BY t1.C#; 
26、查询每门课程被选修的学生数 
select c#,count(S#) from sc group by
C#; 
27、查询出只选修了一门课程的全部学生的学号和姓名 
select SC.S#,Student.Sname,count(C#) AS
选课数 
from SC ,Student 
where SC.S#=Student.S# group by SC.S#
,Student.Sname having count(C#)=1; 
28、查询男生、女生人数 
 Select count(Ssex) as 男生人数 from Student group by Ssex having Ssex='男'; 
 Select count(Ssex) as 女生人数 from Student group by Ssex having Ssex='女'； 
29、查询姓“张”的学生名单 
 SELECT Sname FROM Student WHERE Sname
like '张%'; 
30、查询同名同性学生名单，并统计同名人数 
select Sname,count(*) from Student
group by Sname having count(*)>1;; 
31、1981年出生的学生名单(注：Student表中Sage列的类型是datetime) 
 select Sname, CONVERT(char (11),DATEPART(year,Sage)) as age 
 from student 
 where
CONVERT(char(11),DATEPART(year,Sage))='1981'; 
32、查询每门课程的平均成绩，结果按平均成绩升序排列，平均成绩相同时，按课程号降序排列 
 Select C#,Avg(score) from SC group by
C# order by Avg(score),C# DESC ; 
33、查询平均成绩大于85的所有学生的学号、姓名和平均成绩 
 select Sname,SC.S# ,avg(score) 
 from Student,SC 
 where Student.S#=SC.S# group by
SC.S#,Sname having avg(score)>85; 
34、查询课程名称为“数据库”，且分数低于60的学生姓名和分数 
 Select Sname,isnull(score,0) 
 from Student,SC,Course 
 where SC.S#=Student.S# and
SC.C#=Course.C# and Course.Cname='数据库'and score <60; 
35、查询所有学生的选课情况； 
 SELECT SC.S#,SC.C#,Sname,Cname 
 FROM SC,Student,Course 
 where SC.S#=Student.S# and SC.C#=Course.C#
; 
36、查询任何一门课程成绩在70分以上的姓名、课程名称和分数； 
 SELECT distinct
student.S#,student.Sname,SC.C#,SC.score 
 FROM student,Sc 
 WHERE SC.score>=70 AND
SC.S#=student.S#; 
37、查询不及格的课程，并按课程号从大到小排列 
 select c# from sc where scor e <60
order by C# ; 
38、查询课程编号为003且课程成绩在80分以上的学生的学号和姓名； 
 select SC.S#,Student.Sname from
SC,Student where SC.S#=Student.S# and Score>80 and C#='003'; 
39、求选了课程的学生人数 
 select count(*) from sc; 
40、查询选修“叶平”老师所授课程的学生中，成绩最高的学生姓名及其成绩 
 select Student.Sname,score 
 from Student,SC,Course C,Teacher 
 where Student.S#=SC.S# and SC.C#=C.C#
and C.T#=Teacher.T# and Teacher.Tname='叶平' and
SC.score=(select max(score)from SC where C#=C.C# ); 
41、查询各个课程及相应的选修人数 
 select count(*) from sc group by C#; 
42、查询不同课程成绩相同的学生的学号、课程号、学生成绩 
select distinct A.S#,B.score from SC A ,SC B where A.Score=B.Score and A.C#
<>B.C# ; 
43、查询每门功成绩最好的前两名 
 SELECT t1.S# as 学生ID,t1.C# as 课程ID,Score as 分数 
 FROM SC t1 
 WHERE score IN (SELECT TOP 2 score 
 FROM SC 
 WHERE t1.C#= C# 
 ORDER BY score DESC 
 ) 
 ORDER BY t1.C#; 
44、统计每门课程的学生选修人数（超过10人的课程才统计）。要求输出课程号和选修人数，查询结果按人数降序排列，查询结果按人数降序排列，若人数相同，按课程号升序排列 
 select C# as 课程号,count(*) as
人数 
 from
sc 
 group
by C# 
 order
by count(*) desc,c# 
45、检索至少选修两门课程的学生学号 
 select S# 
 from
sc 
 group
by s# 
 having count(*)
> = 2 
46、查询全部学生都选修的课程的课程号和课程名 
 select C#,Cname
 
 from
Course 
 where
C# in (select
c# from sc group
by c#) 
47、查询没学过“叶平”老师讲授的任一门课程的学生姓名 
 select Sname from Student where S#
not in (select S# from Course,Teacher,SC where Course.T#=Teacher.T# and
SC.C#=course.C# and Tname='叶平'); 
48、查询两门以上不及格课程的同学的学号及其平均成绩 
 select S#,avg(isnull(score,0)) from
SC where S# in (select S# from SC where score <60 group by S# having
count(*)>2)group by S#; 
49、检索“004”课程分数小于60，按分数降序排列的同学学号 
 select S# from SC where C#='004'and
score <60 order by score desc; 
50、删除“002”同学的“001”课程的成绩 
delete from Sc where S#='001'and C#='001';

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