壹 學生 – 課程數據庫
1 查詢 7號課程沒有考試成績的學生學號
select sno from sc where cno=’7’ and grade is null
2 查詢 7號課程成績在90分以上或60分以下的學生學號
select sno from sc where grade>90 or grade<60
3 查詢課程名以“數據”兩個字開頭的所有課程的課程號和課程名。
Select cno,cname from c where cname like ‘數據%’
4 查詢每個學生所有課程的平均成績，輸出學生學號、平均成績
select sno,avg(grade) from sc group by sno
5 查詢每門課程的選修人數，輸出課程號、選修人數。
Select cno,count(*) from sc group by cno
6 查詢選修 7號課程的學生的學號、姓名、性別。
Select s.sno, sname,ssex from s , sc where s.sno=sc.sno and cno = ‘7’
7 查詢選修7號課程學生的平均年齡。
Select avg(sage) from s , sc where s.sno=sc.sno and cno = ‘7’
8 查詢由30名以上學生選修的課程號。
Select sno from sc group by cno having count(*)>30
9 查詢至今沒有考試不及格的學生學號
a: select sno from s where sno not in ( select sno from sc where grade<60 )
b: select sno from sc group by sno having min(grade)>=60
二
1 找出選修課程號為 C2 的學生學號與成績。
Select sno,grade from sc where cno=’C2’
2 找出選修課程號為C4 的學生學號與姓名。
Select s.sno , sname from s,sc where s.sno=sc.sno and cno=’C4’
3 找出選修課程名為 Maths 的學生學號與姓名。
Select s.sno ,sname from s,sc,c
where s.sno=sc.sno and c.cno=sc.cno and cname = ‘Maths’
4找出選修課程號為C2或C4 的學生學號。
Select distinct sno from sc where cno in (‘C2’,’C4’)
或： Select distinct sno from sc where cno=’C2’ or cno =’C4’5找出選修課程號為C2和C4 的學生學號。
Select sno from sc where cno =’C2’ and sno in (
select sno from sc where cno = ‘C4’ )6 找出不學C2課程的學生姓名和年齡
select sname , sage from s where sno not in ( select sno from sc where cno=’C2’ )
或：
select sname , sage from s where not exists ( select * from sc where sc.sno=s.sno and cno=’C2’ )
7 找出選修了數據庫課程的所有學生姓名。(與3同)
Select s.sno ,sname from s,sc,c
where s.sno=sc.sno and c.cno=sc.cno and cname = ‘數據庫’
8 找出數據庫課程不及格的女生姓名
嵌套：
select sname from s where ssex = ‘女’ and sno in ( select sno from sc where grade<60 and cno in ( select cno from c where cname=’數據庫’) )
連接：
Select sname from s,sc,c
where s.sno=sc.sno and c.cno=sc.cno and ssex=’女’ and cname = ‘數據庫’ and grade<609 找出各門課程的平均成績，輸出課程名和平均成績
select cname , avg(grade) from sc , c where c.cno =sc.cno group by sc.cno10找出各個學生的平均成績，輸出學生姓名和平均成績
select sname , avg(grade) from s , sc where s.sno=sc.sno group by sc.sno
11 找出至少有30個學生選修的課程名
select cname from c where cno in ( select cno from sc group by cno having count(*)>=30 )
12 找出選修了不少於3門課程的學生姓名。
Select sname from s where sno in ( select sno from sc group by sno having count(*)>=3)
13 找出各門課程的成績均不低於90分的學生姓名。
Select sname from s where sno not in ( select sno from sc where grade<90)
14* 找出數據庫課程成績不低於該門課程平均分的學生姓名。
Select sname from s where sno in (
Select sno from sc , c where sc.cno=c.cno and cname=’數據庫’ and
Grade > (Select avg(grade) from sc , c where sc.cno=c.cno and cname=’數據庫’ ) )
15 找出各個系科男女學生的平均年齡和人數。
Select sdept,ssex , avg(sage) , count(*) from s
Group by sdept , ssex
16 找出計算機系(JSJ)課程平均分最高的學生學號和姓名。
Select sc.sno , sname from s, sc where s.sno=sc.sno and sdept=’JSJ’
Group by sc.sno Having avg(grade) =
( Select top 1 avg(grade) from sc, s where s.sno=sc.sno and sdept=’JSJ’
group by sc.sno order by avg(grade) DESC )三 客戶 – 商品數據庫中包括3按各表：KH,FP,YWY
1 查詢工資在 1000 到3000 元之間的男性業務員的姓名和辦公室編號。
Select Yname , Ono from YWY where salary between 1000 and 3000 and Ysex=’男’
2 查詢各個辦公室的業務員人數，輸出辦公室編號和對應的人數。
Select Ono , count(*) from YWY group by Ono
3 查詢每個客戶在2002年5月購買的總金額，輸出客戶號和相應的總金額。
Select Kno,sum(Fmoney) from FP where fdate between ‘2002.5.1’ and ‘2002.5.31’
Group by Kno
4 查詢2002年5月購買次數超過5次的所有客戶號，且按客戶號升序排序。
Select Kno from FP where fdate between ‘2002.5.1’ and ‘2002.5.31’
Group by Kno having count(*)>5
Order by Kno ASC
5 查詢各辦公室男性和女性業務員的平均工資。
Select Ono,Ysex ,avg(salary) from YWY group by Ono , Ysex
6 查詢2002年5月曾經在王海亮業務員手中購買過商品的客戶號、客戶姓名、聯系電話。
Select Kno,Kname,phone from KH where Kno in (
Select kno from FP where fdate between ‘2002.5.1’ and ‘2002.5.31’ and
Yno=(select Yno from YWY where Yname = ‘王海亮’ )7 查詢所有工資比1538號業務員高的業務員的編號、姓名、工資。
Select yno ,Yname, salary from YWY where salary >
( Select salary from YWY where Yno=’1538’ )
8 查詢所有與1538號業務員在同壹個辦公室的其他業務員的編號、姓名。
Select Yno , Yname from YWY where Yno<>’1538’ and Ono in (
Select Ono from YWY where Yno=’1538’ )
9 查詢銷售總金額最高的業務員的編號。
Select Yno from FP Group By Yno Having sum(Fmoney) =
(Select top 1 sum(Fmoney) from FP group by Yno ORDER BY sum(Fmoney) DESC)
10 查詢所有業務員的編號、姓名、工資以及工資比他高的其他業務員的平均工資。
利用自身連接
Select y1.Yno ,y1.Yname ,y1.salary , avg( y2. salary) from YWY y1 , YWY y2
Where y1.Yno<>y2.Yno and y1.salary < y2.salary
Group by y1.Yno
Sno salary sno salary
1 100 1 100
2 120 2 120
3 90 3 90
4 110 4 110四 某中學數據庫中由壹張表：
學生選課表：由板及代碼、班內學號、姓名、科目、成績五個屬性組成，關系模式為
SC(BJDM,BNXH,XSXM,KM,CJ) ,其中(BJDM,BNXH)為主碼。
說明：每個學生每門科目存放壹個記錄，科目有“語文”、“數學”、“外語”三門。1 找出每個班級的班級代碼、學生人數、平均成績。
Select BJDM,count(*) ,avg(CJ) from SC group by BJDM
2 找出每個學生的班級代碼、學生姓名、考試科目數、總成績。
Select BJDM,XSXM,count(*) , sum(CJ) from SC
Group by BNXH
3 輸出壹張表格，每位學生對應壹條記錄，包括：班級代碼、姓名、語文成績、數學成績、外語成績。
方法壹：利用視圖
create view v1 (bjdm,xsxm, yw,sx,wy ) AS
select bjdm , xsxm , cj , 0,0 from sc where km=’語文’
union
select bjdm , xsxm , 0 , cj,0 from sc where km=’數學’
union
select bjdm , xsxm , 0,0,cj from sc where km=’外語’select bjdm, xsxm , sum(yw) as 語文, sum(sx) as 數學, sum(wy) as 外語 from v1 group by bjdm, xsxm
方法二:自身連接
select a.bjdm,a.xsxm , a.km,a.cj , b.km,b.cj , c.km,c.cj from sc a , sc b , sc c
where a.bjdm=b.bjdm and a.bnxh= b.bnxh and b.bjdm=c.bjdm and b.bnxh= c.bnxh
and a.km=’語文’ and b.km=’數學’ and c.km=’外語’方法三：利用存儲過程（略）
4 輸出壹張表格：由成績低於60分的每位學生對應壹條記錄，包括字段：班級代碼、姓名、最低成績。Select bjdm,xsxm ,min(CJ) from sc where grade<60 group by bjdm,xsxm5輸出壹張表格：由成績低於60分的每位學生對應壹條記錄，包括字段：班級代碼、姓名、最高成績、平均成績。
得到平均成績：create view V1 (bjdm,bnxh ,avg_cj) AS
select bjdm,bnxh ,avg(cj) from sc where bjdm , bnxhselect sc.bjdm,sc.xsxm ,max(cj) , avg_cj from sc , V1
where sc.bjdm=v1.bjdm and sc.bnxh=V1.bnxh and cj<60
group by sc.bjdm,sc.xsxm6輸出壹張表格：所有成績不低於60分的每位學生對應壹條記錄，包括字段：班級代碼、姓名、平均成績。select bjdm, xsxm , avg(cj) from sc
where sno not in ( select sno from sc where grade<60)
group by bjdm, xsxm7輸出壹張表格：每壹位學生對應壹條記錄，包括字段：班級代碼、姓名、去掉壹個最低分後的平均成績。
方法壹：
得到每個學生的最低分：
create view V1 (bjdm,bnxh ,min_cj) as
select bjdm,bnxh,min(cj) from sc group by bjdm,bnxhselect sc.bjdm,sc.xsxm , avg(cj) from sc , v1
where sc.bjdm=v1.bjdm and sc.bnxh=v1.bnxh and sc.cj <> v1.min_cj
group by bjdm,bnxh方法二：
select sc.bjdm,sc.xsxm , ( sum(cj) – min(cj) ) / count(*) from sc
group by bjdm , bnxh8輸出壹張表格：每門科目對應壹條記錄，包括字段：科目、去掉壹個最低分後的平均成績。
方法壹：
得到每門課的最低分：
create view V1 ( km, min_cj) as
select km,min(cj) from sc group by km
select sc.km , avg(cj) from sc , v1
where sc.km=v1.km and sc.cj <> v1.min_cj
group by sc.km
方法二：
select km , (sum( cj) – min(cj) )/count(*) from sc
group by km補充9：輸出表格：每門科目對應壹條記錄，包括字段：科目、去掉壹個最低分和最高分後的平均成績。
select km , (sum( cj) – min(cj) – max(cj) )/count(*) from sc
group by km五 數據庫存放著某高校1990年以來英語四、六級的考試情況，且規定：
1 英語四、六級考試每年分別在6月和12月舉行二次；
2 四級沒有通過的學生不能報考六級；
3 某壹級的考試只要沒有通過可以反復參加考試；
4 某壹級的考試壹旦通過就不能再報考同級的考試；
5 允許報了名但不參加考試。
該數據庫中有二張表，相應的關系模式如下：
學生表：S(Sno, Sname, Ssex, Sage, Sdept)，其中Sno為主碼。
考試表：E(Sno, Year, Month, Level, Grade)，學號、年、月、級別、成績。
其中(Sno, Year, Month)為主碼。1. 找出各次四級和六級考試的參考人數和平均成績（報了名但沒有參加考試的不作統計）
select year , month,level ,count(*) , avg(grade)
group by year,month , level2. 找出各次四級考試中平均分最高的系科（報了名但沒有參加考試的不作統計）。
A: Select sdept from s , e where s.sno=e.sno
Where level=4
Group by sdept
Having avg(grade)>=ALL(
Select avg(grade) from s , e where s.sno=e.sno where level=4 Group by sdept )B: Select top 1 sdept from s , e where s.sno=e.sno
Where level=4
Group by sdept
Order by (avg(grade) desc
3. 找出已經通過英語六級考試的學生的學號、姓名和性別（用連接方法做）
select s.sno,sname,ssex from s,e
where s.sno=e.sno and level=6 and grade>=60
4. 找出在同壹年中四、六級考試都參加了的學生的學號
1) select sno from E
where (level=4 and grade>=60) or level=6
group by year having count(*)>=22) select sno from E X where level=4 and grade>=60 and exists (
select * from E Y where Y.sno=X.sno and year=X.year and level=6 )5. 找出只參加壹次考試就通過了英語六級考試的學生的學號
select sno from E
where level=6
group by sno
having count(*)=1 錯，想想為何？1) select sno from E
where level=6
group by sno
having count(*)=1 and max(grade)>=602) select sno from E where level=6 and grade>=60 and sno in (
select sno from E where level=6 group by sno having count(*)=1)
6. 找出至今沒有通過英語四級考試的學生的學號（應包括至今還沒有參加過考試或者是參加了但還沒有通過兩種）
select sno from E where level=4
group by sno
having max(grade)<60
Union
Select sno from s where sno not in( select sno from E)
7. 找出英語六級考試中合格人數最少的考試年份和月份（有並列的都要列出，用壹句SQL語句）。
Select year , month From E
Where level = 6 and grade>=60
Group by year , month
Having count(*) <=all
(Select count(*) from E where level=6 and grade>=60 group by year , month )
補充：查詢每門課程的及格率。
1 得到每門課的選修人數 2 得到每門課及格人數 3每門課的及格人數/每門課選修人數1create view v_all( cno , cnt) as select cno , count(*) from sc group by cno
2create view v_pass( cno , cnt_pass) as select cno , count(*) from sc where grade>=60
group by cno
3 select cno , cnt_pass*1.0 / cnt from v_all , v_pass where v_all.cno = v_pass.cno