常见SQL数据库面试题和答案.docx
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 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)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 #,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 #='001'and exists( Select * from SC asSC_2 where #=# and #='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 #=# 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 ,(select score from SC SC_2 where #=# and#='002') score2from Student,SC where #=# 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#,Snamefrom Studentwhere S# not in (select # from Student,SC where #=# and score>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#) <(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 #=# and C# in select C# from SC whereS#='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 #,Snamefrom Student,SCwhere #=# 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 avgfrom SC SC_2where #=# ) from Course,Teacher where #=# and #=# and =' 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 SCfrom course ,Teacherwhere #=# and #= # 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 whereC#='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 FROMSC WHERE #=# ANDC#='004')AS数据库,(SELECT score FROMSC WHERE #=# ANDC#='001')AS企业管理,(SELECT score FROMSC WHERE #=# ANDC#='006')AS英语,COUNT(*) AS 有效课程数 , AVG AS 平均成绩FROM SC AS tGROUP BY S#ORDER BY avg18、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 # As 课程 ID, AS 最高分 , AS 最低分FROM SC L ,SC AS RWHERE # = # and= (SELECT MAXFROM SC AS IL,Student AS IMWHERE # = # and #=#GROUP BY #)AND= (SELECT MINFROM SC AS IRWHERE # = #GROUP BY #);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 # AS 课程号 ,maxAS 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,Coursewhere #=#GROUP BY #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(CASEWHENC# = '001' ANDscore >= 60 THEN1 ELSE 0 END)/SUM(CASEWHEN 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# WHEN'002' 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(CASEC# WHEN'003' 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# WHEN'004' 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
