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1、常见SQL数据库面试题和答案（一）Student(S#,Sname,Sage,Ssex) 学生表龄； Ssex ：学生性别Course(C#,Cname,T#) 课程表教师编号SC(S#,C#,score) 成绩表成绩Teacher(T#,Tname) 教师表S# :学号；Sname学生女4名；Sage：学生年C#,课程编号；Cname课程名字；T#:S#： 学号； C#, 课程编号； scoreT#:教师编号； Tname：教师名字问题：1、查询“ 001”课程比“ 002”课程成绩高的所有学生的学号；select # from (select s#,score from SC where
2、C#=001) a,(select s#,scorefrom SC where C#=002) b where and #=#;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、查询所有同学的学号、姓名、选课数、总成绩；select #,count#),sum(score)from Student left Outer join SC on #=#group by #,Sname4、查询姓“李”的老师的个数；select count(distinct(Tname)fro
3、m Teacherwhere Tname like 李 %;5、查询没学过“叶平”老师课的同学的学号、姓名；select #,from Studentwhere S# not in (select distinct( #) from SC,Course,Teacher where #=# and #=# and = 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 #, from Student,SC where #=# and #=001and exists( Select * from SC asSC_2 where #=# and #=002
4、);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 #=# and #=# and = 叶平 group by S# having count#)=(select count(C#) from Course,Teacher where #=# 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 #,score
5、 ,(select score from SC SC_2 where #=# and#=002) score2from Student,SC where #=# 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 #,from Student,SCwhere #=# group by #, having count(C#) =60 THEN 1 ELSE 0 END)/COUNT(*) AS及格百分数FROM SC T,Coursewhere #=#GROUP BY #ORDER BY 100 * SUM(CASE WHE
6、N 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 001THEN 1 ELSE 0 END) AS 企业管理平均分,100* SUM(CASEWHENC# = 001 ANDscore = 60 THEN1 ELSE 0 END)/SUM(CAS
7、EWHEN C# = 001 THEN 1 ELSE 0 END) AS 企业管理及格百分数,SUM(CASE WHENC# = 002 THENscore ELSE0 END)/SUM(CASEC# WHEN002 THEN 1 ELSE 0 END) AS 马克思平均分,100* SUM(CASEWHENC# = 002 ANDscore = 60 THEN1 ELSE 0 END)/SUM(CASEWHEN C# = 002 THEN 1 ELSE 0 END) AS 马克思及格百分数,SUM(CASE WHENC# = 003 THENscore ELSE0 END)/SUM(CASE
8、C# WHEN003 THEN 1 ELSE 0 END) AS UML 平均分,100* SUM(CASEWHENC# = 003 ANDscore = 60 THEN1 ELSE 0 END)/SUM(CASEWHEN C# = 003 THEN 1 ELSE 0 END) AS UML 及格百分数,SUM(CASE WHENC# = 004 THENscore ELSE0 END)/SUM(CASEC# WHEN004 THEN 1 ELSE 0 END) AS 数据库平均分,100* SUM(CASEWHENC# = 004 ANDscore = 60 THEN1 ELSE 0 END)/SUM(CASEWHEN C# = 004 THEN 1 ELSE 0 END) AS 数据库及格百分数FROM SC