SQL code Student(S#,Sname,Sage,Ssex) 學(xué)生表  Course(C#,Cname,T#) 課程表  SC(S#,C#,score) 成績表  Teacher(T#,Tname) 教師表 
問題：  1、查詢“001”課程比“002”課程成績高的所有學(xué)生的學(xué)號；    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、查詢平均成績大于60分的同學(xué)的學(xué)號和平均成績；      select S#,avg(score)      from sc      group by S# having avg(score) >60;  3、查詢所有同學(xué)的學(xué)號、姓名、選課數(shù)、總成績；    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、查詢姓“李”的老師的個數(shù)；    select count(distinct(Tname))    from Teacher    where Tname like '李%';  5、查詢沒學(xué)過“葉平”老師課的同學(xué)的學(xué)號、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='葉平');  6、查詢學(xué)過“001”并且也學(xué)過編號“002”課程的同學(xué)的學(xué)號、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、查詢學(xué)過“葉平”老師所教的所有課的同學(xué)的學(xué)號、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='葉平' group by S# having count(SC.C#)=(select count(C#) from Course,Teacher  where Teacher.T#=Course.T# and Tname='葉平'));  8、查詢課程編號“002”的成績比課程編號“001”課程低的所有同學(xué)的學(xué)號、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、查詢所有課程成績小于60分的同學(xué)的學(xué)號、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、查詢沒有學(xué)全所有課的同學(xué)的學(xué)號、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、查詢至少有一門課與學(xué)號為“1001”的同學(xué)所學(xué)相同的同學(xué)的學(xué)號和姓名；      select S#,Sname from Student,SC where Student.S#=SC.S# and C# in select C# from SC where S#='1001';  12、查詢至少學(xué)過學(xué)號為“001”同學(xué)所有一門課的其他同學(xué)學(xué)號和姓名；      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“葉平”老師教的課的成績都更改為此課程的平均成績；      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='葉平');  14、查詢和“1002”號的同學(xué)學(xué)習(xí)的課程完全相同的其他同學(xué)學(xué)號和姓名；      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、刪除學(xué)習(xí)“葉平”老師課的SC表記錄；      Delect SC      from course ,Teacher       where Course.C#=SC.C# and Course.T#= Teacher.T# and Tname='葉平';  16、向SC表中插入一些記錄，這些記錄要求符合以下條件：沒有上過編號“003”課程的同學(xué)學(xué)號、2、      號課的平均成績；      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、按平均成績從高到低顯示所有學(xué)生的“數(shù)據(jù)庫”、“企業(yè)管理”、“英語”三門的課程成績，按如下形式顯示： 學(xué)生ID,,數(shù)據(jù)庫,企業(yè)管理,英語,有效課程數(shù),有效平均分      SELECT S# as 學(xué)生ID          ,(SELECT score FROM SC WHERE SC.S#=t.S# AND C#='004') AS 數(shù)據(jù)庫          ,(SELECT score FROM SC WHERE SC.S#=t.S# AND C#='001') AS 企業(yè)管理          ,(SELECT score FROM SC WHERE SC.S#=t.S# AND C#='006') AS 英語          ,COUNT(*) AS 有效課程數(shù), AVG(t.score) AS 平均成績      FROM SC AS t      GROUP BY S#      ORDER BY avg(t.score)   18、查詢各科成績最高和最低的分：以如下形式顯示：課程ID，最高分，最低分      SELECT L.C# As 課程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、按各科平均成績從低到高和及格率的百分?jǐn)?shù)從高到低順序      SELECT t.C# AS 課程號,max(course.Cname)AS 課程名,isnull(AVG(score),0) AS 平均成績          ,100 * SUM(CASE WHEN  isnull(score,0)>=60 THEN 1 ELSE 0 END)/COUNT(*) AS 及格百分?jǐn)?shù)      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、查詢?nèi)缦抡n程平均成績和及格率的百分?jǐn)?shù)(用"1行"顯示): 企業(yè)管理（001），馬克思（002），OO&UML （003），數(shù)據(jù)庫（004）      SELECT SUM(CASE WHEN C# ='001' THEN score ELSE 0 END)/SUM(CASE C# WHEN '001' THEN 1 ELSE 0 END) AS 企業(yè)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 企業(yè)管理及格百分?jǐn)?shù)          ,SUM(CASE WHEN C# = '002' THEN score ELSE 0 END)/SUM(CASE C# WHEN '002' THEN 1 ELSE 0 END) AS 馬克思平均分          ,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 馬克思及格百分?jǐn)?shù)          ,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?jǐn)?shù)          ,SUM(CASE WHEN C# = '004' THEN score ELSE 0 END)/SUM(CASE C# WHEN '004' THEN 1 ELSE 0 END) AS 數(shù)據(jù)庫平均分          ,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 數(shù)據(jù)庫及格百分?jǐn)?shù)    FROM SC