50个常用的SQL语句(答案)

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1、基本信息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.scoreb.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； se

2、lect 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、

3、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.

4、S#=SC.S# and SC.C#=001and 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

5、#)=(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#

6、 and C#=001) S_2 where score2 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#) =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 WHE

7、N 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

8、 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 马克思及格百分数 ,SUM(CASE WHEN C# = 003 THEN score ELSE

9、 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# = 0

10、04 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,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

11、.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），马克思（002），UML （003），数据库（004） 学生ID,学生姓名,企业管理,马克思,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 马克思, T3.score AS UML, T4.score AS 数据库, ISNULL(T1.score,0) + ISNULL(T2.score,0) +

12、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# = 004WHERE student.S#=SC.S# and ISNU

13、LL(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

14、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 ,S

15、UM(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 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

16、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

17、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 Ssex, count(Ssex) as 人数from Studentgroup by Ssex29、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

18、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

19、 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

20、#=Course.C# and Course.Cname=数据库and 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 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

21、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 t

22、1.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(*) d

23、esc,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.

24、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 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#=004and score 60 order by score desc; 50、删除“002”同学的“001”课程的成绩 delete from Sc where S#=001and C#=001;