學生表 Student

create table Student(Sid varchar(6), Sname varchar(10), Sage datetime, Ssex varchar(10));

insert into Student values('01' , '趙雷' , '1990-01-01' , '男');

insert into Student values('02' , '錢電' , '1990-12-21' , '男');

insert into Student values('03' , '孫風' , '1990-05-20' , '男');

insert into Student values('04' , '李云' , '1990-08-06' , '男');

insert into Student values('05' , '周梅' , '1991-12-01' , '女');

insert into Student values('06' , '吳蘭' , '1992-03-01' , '女');

insert into Student values('07' , '鄭竹' , '1989-07-01' , '女');

insert into Student values('08' , '王菊' , '1990-01-20' , '女')

成績表 SC

create table SC(Sid varchar(10), Cid varchar(10), score decimal(18,1));

insert into SC values('01' , '01' , 80);

insert into SC values('01' , '02' , 90);

insert into SC values('01' , '03' , 99);

insert into SC values('02' , '01' , 70);

insert into SC values('02' , '02' , 60);

insert into SC values('02' , '03' , 80);

insert into SC values('03' , '01' , 80);

insert into SC values('03' , '02' , 80);

insert into SC values('03' , '03' , 80);

insert into SC values('04' , '01' , 50);

insert into SC values('04' , '02' , 30);

insert into SC values('04' , '03' , 20);

insert into SC values('05' , '01' , 76);

insert into SC values('05' , '02' , 87);

insert into SC values('06' , '01' , 31);

insert into SC values('06' , '03' , 34);

insert into SC values('07' , '02' , 89);

insert into SC values('07' , '03' , 98)

課程表 Course

create table Course(Cid varchar(10),Cname varchar(10),Tid varchar(10));

insert into Course values('01' , '語文' , '02');

insert into Course values('02' , '數學' , '01');

insert into Course values('03' , '英語' , '03')

教師表 Teacher

create table Teacher(Tid varchar(10),Tname varchar(10));

insert into Teacher values('01' , '張三');

insert into Teacher values('02' , '李四');

insert into Teacher values('03' , '王五')

練習題：

1.查詢" 01 "課程比" 02 "課程成績高的學生的信息及課程分數

select s.*,score

from sdb."Student" s,sdb.sc

where s.Sid=sc.Sid

and s.Sid in(select a.Sid

from sdb.sc a,sdb.sc b

where a.Sid=b.Sid

and a.score>b.score

and a.Cid='01'

and b.Cid='02');

2.查詢平均成績大于等于 60 分的同學的學生編號和學生姓名和平均成績

select s.Sid,Sname,avg(score)

from sdb.sc,sdb."Student" as s

where s.Sid=sc.Sid

group by s.Sid,Sname

having avg(score)>=60;

3.查詢在 SC 表存在成績的學生信息

select *

from sdb.sc,sdb."Student" as s

where s.Sid=sc.Sid

and sc.score is not null;

4.查詢所有同學的學生編號、學生姓名、選課總數、所有課程的總成績(沒成績的顯示為 null )

select s.Sid,Sname,count(Cid),sum(score)

from sdb."Student" s left join sdb.sc

on s.Sid=sc.Sid

group by s.Sid,Sname;

5.查詢「李」姓老師的數量

select count(Tname)

from sdb.teacher as t

where t.Tname like '李%';

6.查詢學過「張三」老師授課的同學的信息

select *

from sdb."Student" as s,sdb.course as c,sdb.teacher as t,sdb.sc

where s.Sid=sc.Sid

and sc.Cid=c.Cid

and c.Tid=t.Tid

and Tname='張三';

7.查詢沒有學全所有課程的同學的信息

select *

from sdb."Student" as s

where s.Sid in (select sc.Sid from sdb.sc group by sc.Sid having count(Cid)<3 )

select s.Sid

from sdb."Student" as s

left join sdb.sc

on s.Sid=sc.Sid

group by s.Sid

having count(sc.Cid)

8.查詢和" 01 "號的同學學習的課程完全相同的其他同學的信息

select s.Sid,Sname,Sage,Ssex

from sdb."Student" s,sdb.sc

where s.Sid=sc.Sid

and s.Sid !='01'

group by s.Sid,Sname,Sage,Ssex

having count(Cid)=(select count(Cid) from sdb.sc where Sid='01');

9.查詢至少有一門課與學號為" 01 "的同學所學相同的同學的信息

select *

from sdb."Student" s

where Sid in (select Sid

from sdb.sc

where Cid in(select Cid

from sdb.sc

where Sid='01'));

10.查詢沒學過"張三"老師講授的任一門課程的學生姓名

select Sname

from sdb."Student" s

where Sid not in(

select s.Sid

from sdb."Student" as s,sdb.course as c,sdb.teacher as t,sdb.sc

where s.Sid=sc.Sid

and sc.Cid=c.Cid

and c.Tid=t.Tid

and Tname like '張三');

11.查詢兩門及其以上不及格課程的同學的學號，姓名及其平均成績

select s.Sid,Sname,avg(score)

from sdb."Student" s,sdb.sc

where s.Sid=sc.Sid

and s.Sid not in (select distinct Sid

from sdb.sc

where score>=60)

group by s.Sid,Sname;

12.檢索" 01 "課程分數小于 60，按分數降序排列的學生信息

select s.*

from sdb."Student" s,sdb.sc

where s.Sid=sc.Sid

and Cid='01'

and score<60

order by score desc;

13.按平均成績從高到低顯示所有學生的所有課程的成績以及平均成績

select score,avg(score)

from sdb.sc

group by score

order by avg(score) desc;

select Sid,

sum(case when Cid='01' then score else null end) score_01,

sum(case when Cid='02' then score else null end) score_02,

sum(case when Cid='03' then score else null end) score_03,

avg(score)

from sdb.sc

group by Sid

order by avg(score) desc;

14.查詢各科成績最高分、最低分和平均分，以如下形式顯示：課程 ID，課程 name，最高分，最低分，平均分，及格率，中等率，優良率，優秀率(及格為>=60，中等為：70-80，優良為：80-90，優秀為：>=90)。

select sc.Cid ,Cname 課程名稱,avg(score) 平均分,max(score) 最高成績,min(score) 最低成績,

(sum(case when score>=60 then 1 else 0 end)*100/count(score)) 及格率,

(sum(case when score>=70 and score<80 then 1 else 0 end)*100/count(score)) 中等率,

(sum(case when score>=80 and score<90 then 1 else 0 end)*100/count(score)) 良好率,

(sum(case when score>=90 then 1 else 0 end )*100/count(score)) 優秀率

from sdb.sc,sdb.course c

where sc.Cid=c.Cid

group by sc.Cid,Cname

15.統計各科成績各分數段人數：課程編號，課程名稱，[100-85]，[85-70]，[70-60]，[60-0] 及所占百分比

select sc.Cid 課程編號,Cname 課程名稱,

(sum(case when score>=0 and score<=60 then 1 else 0 end)*1.00/count(score)) as 不及格0_60,

(sum(case when score>60 and score<=70 then 1 else 0 end)*1.00/count(score)) as 及格60_70,

(sum(case when score>70 and score<=85 then 1 else 0 end)*1.00/count(score)) as 良好70_85,

(sum(case when score>85 and score<=100 then 1 else 0 end)*1.00/count(score)) as 優秀85_100

from sdb.sc,sdb.course c

where sc.Cid=c.Cid

group by sc.Cid,Cname

16.查詢各科成績前三名的記錄

select Cid,Sid,score

from sdb.sc

where (select count(*)

from sdb.sc a

where a.Cid=sc.Cid

and sc.score>a.score)<3

order by Cid,score desc;

select * from (select *,rank() over(partition by Cid order by score desc) as graderank from sdb.sc) a

where a.graderank <=3;

17. 查詢出只選修兩門課程的學生學號和姓名

select s.Sid,Sname

from sdb."Student" s,sdb.sc

where s.Sid=sc.Sid

group by s.Sid,Sname

having count(Cid)=2;

18.查詢名字中含有「風」字的學生信息

select *

from sdb."Student" s

where Sname like '%風%';

19.成績不重復，查詢選修「張三」老師所授課程的學生中，成績最高的學生信息及其成績

select s.Sid,Sname,Ssex,Sage,score

from sdb."Student" as s,sdb.sc

where s.Sid=sc.Sid

group by s.Sid,Sname,Ssex,Sage,score

having max(score)=(select max(score)

from sdb."Student" as s,sdb.course as c,sdb.teacher as t,sdb.sc

where s.Sid=sc.Sid

and sc.Cid=c.Cid

and c.Tid=t.Tid

and Tname like '張三');

總結

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