本人總結(jié)了數(shù)據(jù)庫查詢中一些比較復(fù)雜的查詢，如鏈表查詢，多重子查詢，連表查詢+子查詢等，由于技術(shù)有限，并沒有太多考慮sql語句的優(yōu)化，如有不足之處，敬請諒解。

先來看看表結(jié)構(gòu)：

[sql]?view plaincopyprint?

create?table?student(??

sno?varchar2(10)?primary?key,??

sname?varchar2(20),??

sage?number(2),??

ssex?varchar2(5)??

);??

create?table?teacher(??

tno?varchar2(10)?primary?key,??

tname?varchar2(20)??

);??

create?table?course(??

cno?varchar2(10),??

cname?varchar2(20),??

tno?varchar2(20),??

constraint?pk_course?primary?key?(cno,tno)??

);??

create?table?sc(??

sno?varchar2(10),??

cno?varchar2(10),??

score?number(4,2),??

constraint?pk_sc?primary?key?(sno,cno)??

);??

#/*******初始化學(xué)生表的數(shù)據(jù)******/??

insert?into?student?values?('s001','張三',23,'男');??

insert?into?student?values?('s002','李四',23,'男');??

insert?into?student?values?('s003','吳鵬',25,'男');??

insert?into?student?values?('s004','琴沁',20,'女');??

insert?into?student?values?('s005','王麗',20,'女');??

insert?into?student?values?('s006','李波',21,'男');??

insert?into?student?values?('s007','劉玉',21,'男');??

insert?into?student?values?('s008','蕭蓉',21,'女');??

insert?into?student?values?('s009','陳蕭曉',23,'女');??

insert?into?student?values?('s010','陳美',22,'女');??

commit;??

#/******************初始化教師表***********************/??

insert?into?teacher?values?('t001',?'劉陽');??

insert?into?teacher?values?('t002',?'諶燕');??

insert?into?teacher?values?('t003',?'胡明星');??

commit;??

#/***************初始化課程表****************************/??

insert?into?course?values?('c001','J2SE','t002');??

insert?into?course?values?('c002','Java?Web','t002');??

insert?into?course?values?('c003','SSH','t001');??

insert?into?course?values?('c004','Oracle','t001');??

insert?into?course?values?('c005','SQL?SERVER?2005','t003');??

insert?into?course?values?('c006','C#','t003');??

insert?into?course?values?('c007','JavaScript','t002');??

insert?into?course?values?('c008','DIV+CSS','t001');??

insert?into?course?values?('c009','PHP','t003');??

insert?into?course?values?('c010','EJB3.0','t002');??

commit;??

#/***************初始化成績表***********************/??

insert?into?sc?values?('s001','c001',78.9);??

insert?into?sc?values?('s002','c001',80.9);??

insert?into?sc?values?('s003','c001',81.9);??

insert?into?sc?values?('s004','c001',60.9);??

insert?into?sc?values?('s001','c002',82.9);??

insert?into?sc?values?('s002','c002',72.9);??

insert?into?sc?values?('s003','c002',81.9);??

insert?into?sc?values?('s001','c003',59);??

下面是一些擦尋要求及解答：

[sql]?view plaincopyprint?

#注意：以下練習(xí)中的數(shù)據(jù)是根據(jù)初始化到數(shù)據(jù)庫中的數(shù)據(jù)來寫的SQL?語句，請大家務(wù)必注意。??

#???

#???

#1、查詢“c001”課程比“c002”課程成績高的所有學(xué)生的學(xué)號；??

select?*??from?sc?a,?sc?b?where?a.sno=b.sno?and?a.cno='c001'?and?b.cno='c002'?and?a.score>b.score;??

#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?st.sname,ss.sco?from?student?st,(select?sno,avg(score)sco?from?sc?group?by?sno)ss?where?st.sno=ss.sno?and?sco>=60;??

#3、查詢所有同學(xué)的學(xué)號、姓名、選課數(shù)、總成績；??

select?st.sname,ss.*?from?student?st,(select?sno,count(score)sco,sum(score)?from?sc?group?by?sno)ss?where?st.sno=ss.sno;??

#4、查詢姓“劉”的老師的個數(shù)；??

select?count(*)?from?teacher?where?tname?like?'%劉%';??

#5、查詢沒學(xué)過“諶燕”老師課的同學(xué)的學(xué)號、姓名；??

select?sc.sno,acno.*?from?sc?sc,(select?co.cno?from?course?co,(select?tno?from?teacher?where?tname='諶燕')tn?where?co.tno<>tn.tno)acno?where?acno.cno=sc.cno;??

#6、查詢學(xué)過“c001”并且也學(xué)過編號“c002”課程的同學(xué)的學(xué)號、姓名；??

select?sa.sname,sc.sno?from?sc?sc,(select?st.sname,s.*?from?student?st,(select?sno,cno?from?sc?where?cno?in('c001'))s?where?st.sno=s.sno)sa?where?sc.sno=sa.sno?and?sc.cno='c002';??

#7、查詢學(xué)過“諶燕”老師所教的所有課的同學(xué)的學(xué)號、姓名；??

select?distinct?st.sname?from?student?st,sc?sc?join?(select?cno?from?teacher?te?join?course?co?on(te.tno=co.tno)?where?te.tname='諶燕')aca?on(sc.cno=aca.cno)?where?st.sno=sc.sno;???

#9、查詢所有課程成績小于60?分的同學(xué)的學(xué)號、姓名；??

select?st.sname,sc.sno?from?student?st?join?sc?sc?on(st.sno=sc.sno)where?sc.score<60;??

#10、查詢沒有學(xué)全所有課的同學(xué)的學(xué)號、姓名；??

select?sname,st.sno,scn.cn?from?student?st?join?(select?distinct?sno,count(*)cn?from?sc?group?by?sc.sno)scn?on(st.sno=scn.sno)?where?scn.cn=(select?distinct?count(cno)?from?course);??

select?st.sname,st.sno?from?student?st?join?(select?sc.sno?sn,count(sc.cno)?cou?from?sc?group?by?sc.sno)?scs?on?st.sno=scs.sn?where?scs.cou?<(select?count(cno)?from?course);??

#11、查詢至少有一門課與學(xué)號為“s001”的同學(xué)所學(xué)相同的同學(xué)的學(xué)號和姓名；??

select?distinct?st.sno,?sname??

??from?student?st??

??join?sc?sc?on?(st.sno?=?sc.sno)??

?where?sc.cno?in?(select?cno?from?sc?where?sno?=?'s001')?and?sc.sno<>'s001';??

[sql]?view plaincopyprint?

#13、把“SC”表中“諶燕”老師教的課的成績都更改為此課程的平均成績；??

#update?sc?sc?set?sc.score=update?sc?sc?set?sc.score=(select?tc.cno,round(avg(sc.score),2)av?from?(select?*?from?teacher?te?join?course?co?on(te.tno=co.tno)?where?te.tname='諶燕')tc?join?sc?sc?on(tc.cno=sc.cno)?group?by?tc.cno)cnn.score?where?sc.cno=cnn.av;??

select?tc.cno,round(avg(sc.score),2)?from?(select?*?from?teacher?te?join?course?co?on(te.tno=co.tno)?where?te.tname='諶燕')tc?join?sc?sc?on(tc.cno=sc.cno)?group?by?tc.cno;??

#14、查詢和“s001”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?cno?from?sc?where?sno='s001';??

#15、刪除學(xué)習(xí)“諶燕”老師課的SC?表記錄；??

delete?from?sc?where?sc.cno?in(select?cno?from?teacher?te?join?course?co?on(te.tno=co.tno)?where?te.tname='諶燕')??

#17、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?cno,max(score),min(score)?from?sc?group?by?cno;??

#18、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?count(score)?from?sc?where?score>=60?group?by?cno?;??

select?cno,avg(score)acs,savg.cnu,(count(score)-savg.cnu)/count(score)*100?from?sc,??

(select?count(score)cnu,avg(score)acs2?from?sc?where?score<60?order?by?acs2?desc)savg???

group?by?savg.cnu,cno?order?by?acs?desc;??

#21、查詢各科成績前三名的記錄:(不考慮成績并列情況)??

select?*?from?(select?S.*,rownum?rn?from?(select?*?from?sc?order?by?score?desc)S?where?rownum<=3)where?rn>=1;??

#22、查詢每門課程被選修的學(xué)生數(shù)??

select?cno,count(cno)?from?sc?group?by?cno;??

#23、查詢出只選修了一門課程的全部學(xué)生的學(xué)號和姓名??

select?st.sname,st.sno?from?student?st?join???

(select?distinct?sc.*?from?sc?sc?join?(select?sno,count(cno)cnum?from?sc?group?by?sno)ss?on(sc.sno=ss.sno)?where?ss.cnum=1)ssb???

on(st.sno=ssb.sno);??

#24、查詢男生、女生人數(shù)??

select?ssex,count(ssex)?from?student?st?group?by?ssex;??

#25、查詢姓“張”的學(xué)生名單??

select?sname?from?student?where?sname?like?'%張%';??

#26、查詢同名同性學(xué)生名單，并統(tǒng)計同名人數(shù)??

select?st.*?from?student?st?join?(select?sname,count(sname)cnum?from?student?group?by?sname)scomm?on(st.sname=scomm.sname)?where?scomm.cnum>1;??

#27、1981?年出生的學(xué)生名單(注：Student?表中Sage?列的類型是number)??

select?*?from?student?where?to_char(sysdate,'yyyy')-sage?='1981';??

#28、查詢每門課程的平均成績，結(jié)果按平均成績升序排列，平均成績相同時，按課程號降序排列??

select?cno,avg(score)lim?from?sc?group?by?cno?order?by?lim?asc;??

#29、查詢平均成績大于85?的所有學(xué)生的學(xué)號、姓名和平均成績??

select?st.sname,st.sno,savg.lim?from?student?st?join?(select?sno,avg(score)lim?from?sc?group?by?sno)savg?on(st.sno=savg.sno)?where?savg.lim>85;??

#30、查詢課程名稱為“數(shù)據(jù)庫”，且分?jǐn)?shù)低于60?的學(xué)生姓名和分?jǐn)?shù)??

select?distinct?st.sname,cs.score?from?student?st?join?(select?*?from?course?co?join?sc?sc?on(co.cno=sc.cno))cs?on(st.sno=cs.sno)where?cs.score<60?and?cs.cname='數(shù)據(jù)庫';??

#31、查詢所有學(xué)生的選課情況；??

select?distinct?st.sname,cs.cname?from?student?st?join?(select?*?from?course?co?join?sc?sc?on(co.cno=sc.cno))cs?on(st.sno=cs.sno);??

#32、查詢?nèi)魏我婚T課程成績在70?分以上的姓名、課程名稱和分?jǐn)?shù)；??

select?distinct?st.sname,cs.score,cs.cname?from?student?st?join?(select?*?from?course?co?join?sc?sc?on(co.cno=sc.cno))cs?on(st.sno=cs.sno)where?cs.score>70;??

#33、查詢不及格的課程，并按課程號從大到小排列??

select?*?from?sc?where?score<60?order?by?sno?desc;??

#34、查詢課程編號為c001?且課程成績在80?分以上的學(xué)生的學(xué)號和姓名；??

select?st.sname,st.sno?from?student?st?join?(select?*?from?sc?where?cno='c001'?and?score>80)snum?on(st.sno=snum.sno);??

#35、求選了課程的學(xué)生人數(shù)??

select?count(ss.sno)?from?(select?distinct?sno?from?sc)ss;??

#36、查詢選修“諶燕”老師所授課程的學(xué)生中，成績最高的學(xué)生姓名及其成績??

select?st.sname,cnum.score?from?student?st?join??

(select?distinct?*?from?sc?sc?where?cno?in(select?distinct?cno?from?course?co?join???

(select?tno?from?teacher?where?tname='諶燕')ten?on(co.tno=ten.tno))?order?by?score?desc)cnum?on(st.sno=cnum.sno)?where?rownum=1;??

#37、查詢各個課程及相應(yīng)的選修人數(shù)??

#(select?cno,count(cno)?from?sc?group?by?cno);??

select?co.cname,cns.cnum?from?course?co?join?(select?cno,count(cno)cnum?from?sc?group?by?cno)cns?on(co.cno=cns.cno);??

#39、查詢每門功課成績最好的前兩名??

select?cno?from?sc?order?by?score?desc?group?by?cno;??

#40、統(tǒng)計每門課程的學(xué)生選修人數(shù)（超過10?人的課程才統(tǒng)計）。要求輸出課程號和選修人數(shù)，查詢結(jié)果按人數(shù)降序排列，若人數(shù)相同，按課程號升序排列??

#41、檢索至少選修兩門課程的學(xué)生學(xué)號??

select?sno?from?(select?sno,count(cno)cnum?from?sc?group?by?sno)?where?cnum>=2;??

#42、查詢?nèi)繉W(xué)生都選修的課程的課程號和課程名??

#select?count(*)?from?(select?distinct?sno?from?sc);??

#select?cno,count(cno)cns?from?sc?group?by?cno;??

#select?cno?from?(select?count(*)num?from?(select?distinct?sno?from?sc))cs1,(select?cno,count(cno)cns?from?sc?group?by?cno)cs2?where?cs2.cns=cs1.num;??

select?cname,scs.cno?from?course?co?join???

(select?cno?from?(select?count(*)num?from?(select?distinct?sno?from?sc))cs1,??

(select?cno,count(cno)cns?from?sc?group?by?cno)cs2?where?cs2.cns=cs1.num)scs?on(co.cno=scs.cno);??

#43、查詢沒學(xué)過“諶燕”老師講授的任一門課程的學(xué)生姓名??

#select?co.cno?from?course?co?join?(select?tno?from?teacher?where?tname='諶燕')tn?on(co.tno=tn.tno);??

select?sname?from?student?where?sno?not?in??

(select?distinct?sno?from?sc?where?cno?in(select?co.cno?from?course?co?join???

(select?tno?from?teacher?where?tname='諶燕')tn?on(co.tno=tn.tno)));??

#44、查詢兩門以上不及格課程的同學(xué)的學(xué)號及其平均成績??

#select?sno,count(sno),avg(score)?from?sc?where?score?<?60?group?by?sno;??

select?*?from?(select?sno,count(sno)cnum,avg(score)?from?sc?where?score?<?60?group?by?sno)avs?where?avs.cnum>1;??

#45、檢索“c004”課程分?jǐn)?shù)小于60，按分?jǐn)?shù)降序排列的同學(xué)學(xué)號??

select?sno?from?sc?where?cno='c004'?and?score<60?order?by?score?desc;??

#46、刪除“s002”同學(xué)的“c001”課程的成績??

delete?from?sc?where?sno='s002'?and?cno='c001'; ?

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