面试中常用的SQL语句.docx

1、面试中常用的SQL语句面试中常用的SQL语句（数据库知识必杀） 来源：中联无限科技有限公司 发布日期：2010-10-19 10:15:13 收藏到： 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； 中联无限科技公司提供专业的成都网站建设、成都网站设计、成都网站制作、成都网站推广。Student(S#,Sname,Sage,Ssex) 学生表Course(C#,Cname,T#

2、) 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#,scorefrom SC where C#=002) bwhere 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；select S#,avg(score)from scgroup by S# having avg(score) 60;3、查询

3、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#,Sname4、查询姓“李”的老师的个数；select count(distinct(Tname)from Teacherwhere 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.Snamefrom Studentwhere S#

4、 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#=001and exists( Select * from SC as SC_2 where SC_2.S#=SC.S#

5、 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#,Snamefrom Studentwhere 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);

6、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) score2from Student,SC where Student.S#=SC.S# and C#=001) S_2 where score2 9、查询所有课程成绩小于60分的同学的学号、姓名；select S#,Snamefrom Studentwhe

7、re S# not in (select Student.S# from Student,SC where S.S#=SC.S# and score60);10、查询没有学全所有课的同学的学号、姓名；select Student.S#,Student.Snamefrom Student,SCwhere 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,Coursewhere t.C#=course.C#GROU

8、P BY t.C#ORDER BY 100 * SUM(CASE WHEN isnull(score,0)=60 THEN 1 ELSE 0 END)/COUNT(*) DESC20、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

9、 = 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(CAS

10、E 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

11、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 SC21、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 Zwhere T.C#=C.C# a

12、nd C.T#=Z.T#GROUP BY C.C#ORDER BY AVG(Score) DESC22、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 3SC.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.

13、score,0) + ISNULL(T3.score,0) + ISNULL(T4.score,0) as 总分FROM Student,SC LEFT JOIN SC AS T1ON SC.S# = T1.S# AND T1.C# = 001LEFT JOIN SC AS T2ON SC.S# = T2.S# AND T2.C# = 002LEFT JOIN SC AS T3ON SC.S# = T3.S# AND T3.C# = 003LEFT JOIN SC AS T4ON SC.S# = T4.S# AND T4.C# = 004WHERE student.S#=SC.S# andIS

14、NULL(T1.score,0) + ISNULL(T2.score,0) + ISNULL(T3.score,0) + ISNULL(T4.score,0)NOT IN(SELECTDISTINCTTOP 15 WITH TIESISNULL(T1.score,0) + ISNULL(T2.score,0) + ISNULL(T3.score,0) + ISNULL(T4.score,0)FROM scLEFT JOIN sc AS T1ON sc.S# = T1.S# AND T1.C# = k1LEFT JOIN sc AS T2ON sc.S# = T2.S# AND T2.C# =

15、k2LEFT JOIN sc AS T3ON sc.S# = T3.S# AND T3.C# = k3LEFT JOIN sc AS T4ON sc.S# = T4.S# AND T4.C# = k4ORDER 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, 60SELECT SC.C# as 课程ID, Cname as 课程名称,SUM(CASE WHEN sc

16、ore 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 SCGROUP BY S#) AS T2ORDE

17、R 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 t1WHERE score IN (SELECT TOP 3 scoreFROM SCWHERE 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,cou

18、nt(C#) AS 选课数from SC ,Studentwhere 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

19、 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 agefrom studentwhere 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

20、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,SCwhere 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,Coursewhere SC

21、.S#=Student.S# and SC.C#=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,scorefrom Student,SC,Course C,Teacherwhere Studen

22、t.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

23、名SELECT t1.S# as 学生ID,t1.C# as 课程ID,Score as 分数FROM SC t1WHERE score IN (SELECT TOP 2 scoreFROM SCWHERE 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 scgroup 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 scgroup by s#having c