SQL查詢語句練習

創建四個表，分別是學生表，課程表，成績表和教師信息表

插入信息：

題目：

一、 查詢Student表中的全部記錄的Sname、Ssex和Class列

     select Sname,Ssex,Class from Student 

二、 查詢教師全部的單位即不重複的Depart列。

     select distinct Depart from Teacher

三、 查詢Student表的全部記錄。

     select * from student

四、 查詢Score表中成績在60到80之間的全部記錄。

     select * from Score where Degree between 60 and 80

五、 查詢Score表中成績爲85，86或88的記錄。

     select * from Score where Degree in (85,86,88)

六、 查詢Student表中「95031」班或性別爲「女」的同窗記錄。

select * from student where Class = 95031 or Ssex = '女'

七、 以Class降序查詢Student表的全部記錄。

select * from student order by Class desc

八、 以Cno升序、Degree降序查詢Score表的全部記錄。

select * from Score order by Cno asc ,Degree desc

九、 查詢「95031」班的學生人數。

select COUNT (*) 人數 from student where Class =95031

十、 查詢Score表中的最高分的學生學號和課程號。（子查詢或者排序）

select Sno,cno from Score where Degree =(select MAX (Degree ) from Score )

十一、 查詢每門課的平均成績。

select AVG(Degree) 平均成績 from Score group by Cno

十二、查詢Score表中至少有5名學生選修的並以3開頭的課程的平均分數。

select AVG (Degree ) from Score where Cno like '3%' group by Cno having COUNT (*)>=5

思路：先把score表查詢出來，而後用函數avg把score表的平均分查詢出來，而後用where條件句把以3開頭的課程這個條件篩選出來，

最後用having把5個學生選修這個條件篩選出來

1三、查詢分數大於70，小於90的Sno列。

select Sno from Score where Degree >70 and Degree <90

1四、查詢全部學生的Sname、Cno和Degree列。

select sname,cno,degree from score left join student on student.sno=score.sno

1五、查詢全部學生的Sno、Cname和Degree列。

select cname,sno,degree from score join course on course.cno=score.cno

1六、查詢全部學生的Sname、Cname和Degree列。

select cname,sname,degree from score join course on course.cno=score.cno join student on student.sno=score.sno

1七、 查詢「95033」班學生的平均分。

select AVG (Degree ) from Score where Sno in(select Sno from student where Class ='95033')

1八、 假設使用以下命令創建了一個grade表：

create table grade(low  int(3),upp  int(3),rank  char(1))

insert into grade values(90,100,’A’)

insert into grade values(80,89,’B’)

insert into grade values(70,79,’C’)

insert into grade values(60,69,’D’)

insert into grade values(0,59,’E’)

現查詢全部同窗的Sno、Cno和rank列。

1九、  查詢選修「3-105」課程的成績高於「109」號同窗成績的全部同窗的記錄。

select * from Score where Cno ='3-105' and Degree > any (select Degree from Score where Sno ='105')

20、查詢score中選學多門課程的同窗中分數爲非最高分紅績的記錄。

解一、

select * from Score where Sno in (select Sno from Score where Sno !=(select * from Score where Degree ='91') group by Sno having COUNT (*)>1)

思路：

解二、

select * from Score where Sno in (select Sno from Score where Sno
!=(select * from Score where Degree ='91') group by Sno having COUNT (*)>1)

思路：

2一、 查詢成績高於學號爲「109」、課程號爲「3-105」的成績的全部記錄。

select * from Score where Cno='3-105' and Degree > any (select Degree from Score where Sno=109)

2二、查詢和學號爲108的同窗同年出生的全部學生的Sno、Sname和Sbirthday列。

select Sno,Sname ,Sbrithday from student where YEAR (Sbrithday )= (select YEAR (Sbrithday ) from student where Sno =108)

2三、查詢「張旭「教師任課的學生成績。

select * from score where cno in (select cno from course where tno in(select tno from teacher where tname='張旭' ))

2四、查詢選修某課程的同窗人數多於5人的教師姓名。

select Tname from Teacher where Tno in (select Tno from Course where Cno in (select Cno from Score group by Cno having COUNT (*)>=5))

思路：先把這個題用到的teacher，score，course表查詢出來看一下，先用group by和having 把同窗人數多於五人的課程代號這個條件篩選出來，

而後再把教這個課程的老師代號查詢出來，知道老師的代號以後再把老師的姓名查詢出來

2五、查詢95033班和95031班全體學生的記錄。

select * from student where Class in(95033,95031)

2六、  查詢存在有85分以上成績的課程Cno.

select distinct Cno from Score where Degree >85

2七、查詢出「計算機系「教師所教課程的成績表。

select * from course where tno in (select tno from teacher where depart='計算機系')

2八、查詢「計算機系」與「電子工程系「不一樣職稱的教師的Tname和Prof。

select * from Teacher where Depart ='計算機系' and Prof not in (select Prof from Teacher where Depart ='電子工程系')
union
select * from Teacher where Depart ='電子工程系' and Prof not in (select Prof from Teacher where Depart ='計算機系')

2九、查詢選修編號爲「3-105「課程且成績至少高於選修編號爲「3-245」的同窗的Cno、Sno和Degree,並按Degree從高到低次序排序。

select * from Score where Cno ='3-105' and Degree >(select MAX(Degree ) from Score where Cno ='3-245') order by Degree desc

思路：先把score表中課程號是3-245的平均成績查詢出來，而後在查詢一下score表中課程號是3-105的而且成績大於86的，按降序排列

30、查詢選修編號爲「3-105」且成績高於選修編號爲「3-245」課程的同窗的Cno、Sno和Degree.

select * from Score s1 where Sno in(103,109,105) and Cno ='3-105' and exists(
select * from Score s2 where Sno in(103,109,105) and Cno ='3-245' and s1.Sno =s2.Sno and s1.Degree >s2.Degree )

思路：

3一、 查詢全部教師和同窗的name、sex和birthday.

select Tname ,Tsex ,Tbrithday from Teacher
union
select Sname ,Ssex ,Sbrithday from student

3二、查詢全部「女」教師和「女」同窗的name、sex和birthday.

select Tname ,Tsex ,Tbrithday from Teacher where Tsex ='女'
union
select Sname ,Ssex ,Sbrithday from student where Ssex ='女'

3三、 查詢成績比該課程平均成績低的同窗的成績表。

select * from Score s1 where exists (
select Cno,AVG (Degree ) from Score s2 group by Cno having s1.Cno =s2.Cno and s1.Degree <AVG(Degree ) )

3四、 查詢全部任課教師的Tname和Depart.

解一、

select Tname,Depart from Teacher where exists
(select * from Course where Teacher.Tno =Course.Tno )

解二、

select Tname ,Depart  from Teacher where Tno in (select distinct Tno  from Course )

解三、

select Tname ,Depart from Course left join Teacher on Teacher.Tno =Course.Tno

35 、 查詢全部未講課的教師的Tname和Depart. 

select * from teacher where tno not in (select tno from course )

3六、查詢至少有2名男生的班號。

select Class from student where Ssex ='男' group by Class having COUNT (* )>=2

3七、查詢Student表中不姓「王」的同窗記錄。

select * from student where Sname not like '王%'

3八、查詢Student表中每一個學生的姓名和年齡。

select sname, datediff(YEAR,Sbrithday ,'2014-11-9') 年齡 from student

3九、查詢Student表中最大和最小的Sbirthday日期值。

select MAX (Sbrithday) 最大值,MIN (Sbrithday ) 最小值 from student

40、以班號和年齡從大到小的順序查詢Student表中的所有記錄。

select * from student order by Class desc,Sbrithday asc

4一、查詢「男」教師及其所上的課程。

select Cno from Course where Tno in(select Tno from Teacher where Tsex = '男')

4二、查詢最高分同窗的Sno、Cno和Degree列。

select Sno,Cno ,Degree from Score where Degree in (select MAX (Degree ) from Score)

4三、查詢和「李軍」同性別的全部同窗的Sname.

select Sname from student where ssex= (select Ssex from student where Sname ='李軍')

4四、查詢和「李軍」同性別並同班的同窗Sname.

select Sname from student where Class in(select Class from student where Sname ='李軍')
and Ssex =(select Ssex from student where Sname ='李軍')

4五、查詢全部選修「計算機導論」課程的「男」同窗的成績表。

select * from Score where Cno in(select Cno from Course where Cname ='計算機導論') and Sno in(select Sno from student where Ssex ='男')