經典50個SQL語句大全

 　　50個常用的sql語句

　　Student(S#,Sname,Sage,Ssex) 學生表

　　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生的學號;

　　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、查詢平均成績大於60分的同學的學號和平均成績;

　　select S#,avg(score)

　　from sc

　　group by S# having avg(score) >60;

　　3、查詢所有同學的學號、姓名、選課數、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;

　　select count(distinct(Tname))

　　from Teacher

　　where Tname like '李%';

　　5、查詢沒學過“葉平”老師課的同學的學號、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、查詢學過“001”並且也學過編號“002”課程的同學的學號、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、查詢學過“葉平”老師所教的所有課的同學的學號、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”課程低的所有同學的學號、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

　　9、查詢所有課程成績小於60分的同學的學號、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、查詢沒有學全所有課的同學的學號、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號為“1001”的同學所學相同的同學的學號和姓名;

　　select S#,Sname from Student,SC where Student.S#=SC.S# and C# in select C# from SC where S#='1001';

　　12、查詢至少學過學號為“001”同學所有一門課的其他同學學號和姓名;

　　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”號的同學學習的課程完全相同的其他同學學號和姓名;

　　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、刪除學習“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”課程的同學學號、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生的“數據庫”、“企業管理”、“英語”三門的課程成績，按如下形式顯示： 學生ID,,數據庫,企業管理,英語,有效課程數,有效平均分

　　SELECT S# as 學生ID

　　,(SELECT score FROM SC WHERE SC.S#=t.S# AND C#='004') AS 數據庫

　　,(SELECT score FROM SC WHERE SC.S#=t.S# AND C#='001') AS 企業管理

　　,(SELECT score FROM SC WHERE SC.S#=t.S# AND C#='006') AS 英語

　　,COUNT(*) AS 有效課程數, 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數從高到低順序

　　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 及格百分數

　　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、查詢如下課程平均成績和及格率的百分數(用"1行"顯示): 企業管理(001)，馬克思(002)，OO&UML (003)，數據庫(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 企業管理及格百分數

　　,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 馬克思及格百分數

　　,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及格百分數

　　,SUM(CASE WHEN C# = '004' THEN score ELSE 0 END)/SUM(CASE C# WHEN '004' THEN 1 ELSE 0 END) AS 數據庫平均分

　　,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 數據庫及格百分數

　　FROM SC

　　21、查詢不同老師所教不同課程平均分從高到低顯示

　　SELECT max(Z.T#) AS 教師ID,MAX(Z.Tname) AS 教師姓名,C.C# AS 課程ID,MAX(C.Cname) AS 課程名稱,AVG(Score) AS 平均成績

　　FROM SC AS T,Course AS C ,Teacher AS Z

　　where T.C#=C.C# and C.T#=Z.T#

　　GROUP BY C.C#

　　ORDER BY AVG(Score) DESC

　　22、查詢如下課程成績第 3 名到第 6 名的學生成績單：企業管理(001)，馬克思(002)，UML (003)，數據庫(004)

　　[學生ID],[學生姓名],企業管理,馬克思,UML,數據庫,平均成績

　　SELECT DISTINCT top 3

　　SC.S# As 學生學號,

　　Student.Sname AS 學生姓名 ,

　　T1.score AS 企業管理,

　　T2.score AS 馬克思,

　　T3.score AS UML,

　　T4.score AS 數據庫,

　　ISNULL(T1.score,0) + ISNULL(T2.score,0) + ISNULL(T3.score,0) + ISNULL(T4.score,0) as 總分

　　FROM Student,SC LEFT JOIN SC AS T1

　　ON SC.S# = T1.S# A