一、設置數據庫

包括四個表：學生表（Student）、課程表（Course）、成績表（Score）以及教師信息表（Teacher）。四個表的結構分別如表1-1的表（一）~表（四）所示，數據如表1-2的表（一）~表（四）所示。用SQL語句創建四個表並完成相關題目。

# 創建數據庫
create database if not exists z_stu;

#創建學生表（Student）
/*
屬性名    數據類型    可否為空    含 義
Sno        varchar (20)    否            學號（主碼）
Sname    varchar (20)    否        學生姓名
Ssex        varchar (20)    否        學生性別
Sbirthday    Datetime        可        學生出生年月
 Class    varchar (20)    可        學生所在班級
 
*/
create  table  if not exists student(
    sno varchar(20) not null comment"學號",
    sname varchar(20) not null comment"學生姓名",
    ssex varchar(20) not null comment"性別",
    sbirthday    datetime comment"生日",
    class varchar(20) comment"班級",
    primary key(sno)
)charset = utf8;

#創建課程表（Course）
/*
屬性名    數據類型    可否為空    含 義
Cno        varchar (20)        否        課程號（主碼）
Cname    varchar (20)        否        課程名稱
Tno        varchar (20)        否        教工編號（外碼）
 
*/
create  table  if not exists course(
    cno varchar(20) not null comment"課程號",
    cname varchar(20) not null comment"課程名稱",
    tno varchar(20) not null comment"老師編號",
    primary key(cno)    
)charset utf8;

#創建成績表（Score）

/*
屬性名    數據類型    可否為空    含 義
Sno        varchar (20)        否        學號（外碼）
Cno        varchar (20)        否        課程號（外碼）
Degree    Decimal(4,1)        可        成績
                        
主碼：Sno+ Cno
 
*/
create table  if not exists score(
    sno varchar(20) not null comment"學號",
    cno varchar(20) not null comment"課程號",
    degree decimal(4,1),
    primary key(sno,cno)
)charset utf8;

#創建老師表（Teacher）
/*
屬性名        數據類型    可否為空    含 義
Tno            varchar (20)        否        教工編號（主碼）
Tname        varchar (20)        否        教工姓名
Tsex            varchar (20)            否        教工性別
Tbirthday        datetime            可        教工出生年月
Prof            varchar (20)            可        職稱
Depart        varchar (20)        否        教工所在部門
*/
create table if not exists teacher(
    tno varchar(20) not null comment"教工編號",
    tname varchar(20) not null comment"教師姓名",
    tsex varchar(20) not null comment"性別",
    tbirthday datetime comment"生日",
    prof varchar(20) comment"職稱",
    depart varchar(20) not null comment"教工所在部門",
    primary key(tno)
)charset utf8;

　　開始給表添加數據（增）

學生表（Student）

insert into student values
("108","曾華","男","1977-09-01","95033"),
("105","匡明","男","1975-10-02","95031"),
("107","王麗","女","1976-01-23","95033"),
("101","李軍","男","1976-02-20","95033"),
("109","王芳","女","1975-02-10","95031"),
("103","陸君","男","1974-06-03","95031");

　課程表（Course）

insert into course values
("3-105","計算機導論","825"),
("3-245","操作系統","804"),
("6-166","數字電路","856"),
("9-888","高等數學","831");

　成績表（Score）

insert into score values
("103","3-245","86"),
("105","3-245","75"),
("109","3-245","68"),
("103","3-105","92"),
("105","3-105","88"),
("109","3-105","76"),
("101","3-105","64"),
("107","3-105","91"),
("108","3-105","78"),
("101","6-166","85"),
("107","6-166","79"),
("108","6-166","81");

　教師表（Teacher）　

insert into teacher values
("804","李誠","男","1958-12-02","副教授","計算機系"),
("856","張旭","男","1969-03-12","講師","電子工程系"),
("825","王萍","女","1972-05-05","助教","計算機系 "),
("831","劉冰","女","1977-08-14","助教","電子工程系");

修改數據（改）：

把姓名為“李軍”的性別改為“女”

update student set ssex="女" where sname="李軍";

查看表（查）：

select * from student;
select * from course;
select * from score;
select * from teacher;

刪除數據（刪，以行為單位）：

delete from student where sno in(101,103);

　查看數據所有的實例：　

#1、 查詢Student表中的所有記錄的Sname、Ssex和Class列。
select sname,ssex,class from student;
#2、 查詢教師所有的單位即不重復的Depart列。
 select distinct depart from teacher; 
#3、 查詢Student表的所有記錄。
select * from student;
#4、 查詢Score表中成績在60到80之間的所有記錄。
select * from score where degree  between 60 and 80;
#5、 查詢Score表中成績為85，86或88的記錄。
select * from score where degree in(85,86,88);
#6、 查詢Student表中“95031”班或性別為“女”的同學記錄。
select * from student where class = "95031" or ssex = "女";
 #以Class降序查詢Student表的所有記錄。
select * from student order by class desc;
# 以Cno升序、Degree降序查詢Score表的所有記錄。
select * from score order by cno,degree desc;
 #查詢“95031”班的學生人數。
select count(*) from student group by class having class="95033";
#10、 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 max(degree) from score;
select sno,cno from score where degree=(select max(degree) from score);
# 查詢每門課的平均成績。
select cno,avg(degree) from score group by cno;
#12、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 group by cno having cno like"3%" and count(*)>=5 ;
#查詢分數大於70，小於90的Sno列。
select sno from score where degree between 70 and 90;
#查詢所有學生的Sname、Cno和Degree列。
select student.sname,score.cno,score.degree from student
join score on student.sno=score.sno;
#15、查詢所有學生的Sno、Cname和Degree列。
select student.sno,course.cname,score.degree from student
join score on score.sno=student.sno
join course on course.cno=score.cno;
#16、查詢所有學生的Sname、Cname和Degree列。
select a.sname,b.cname,c.degree
from student as a,course as b,score as c
where a.sno = c.sno and b.cno = c.cno;
select sname,cname,degree from student join score on student.sno=score.sno  join course on course.cno=score.cno;
#17、 查詢“95033”班學生的平均分。
select sno from student where class="95033";
select avg(degree) from score where sno in(select sno from student where class="95033");
#1.查詢選修“3-105”課程的成績高於“109”號同學成績的所有同學的記錄。
#20、查詢score中選學多門課程的同學中分數為非最高分成績的記錄。
#選修多門課的學生
select sno,count(*) from score group by sno;
#找到最高分
select max(degree) from score
select * from score where sno in(select sno from score group by sno)and degree<(select max(degree) from score);
#21、 查詢成績高於學號為“109”、課程號為“3-105”的成績的所有記錄。
select degree from score where sno="109" and cno="3-105";
select degree from score where degree>(select degree from score where sno="109" and cno="3-105");
#22、查詢和學號為108的同學同年出生的所有學生的Sno、Sname和Sbirthday列。
select left(sbirthday,4) as date from student;
select sno,sname,sbirthday from student where sbirthday like concat((select left(sbirthday,4) as date from student where sno="108"),"","%");
#23、查詢“張旭“教師任課的學生成績。
#1、從成績表 查詢學生成績  
#2、條件是這個課程是 “張旭“教師任課
#A)從老師表 中查名字叫 張旭 編號
#B)根據老師編號 在課程表中找到對應的 課程
select  depart from teacher where tname="張旭";
select cno from course where depart=(select  depart from teacher where tname="張旭");
#24、查詢選修某課程的同學人數多於5人的教師姓名。
select cno from score group by cno having count(*)>"5";
select tno from course where cno in(select cno from score group by cno having count(*)>"5");
select tname from teacher where tno=(select tno from course where cno in(select cno from score group by cno having count(*)>"5"));
#25、查詢95033班和95031班全體學生的記錄。
select * from student where class in(95033,95031);
#26、  查詢存在有85分以上成績的課程Cno.
select cno from score where degree>"85";
#27、查詢出“計算機系“教師所教課程的成績表。
select tno from teacher where depart="計算機系";
select cno from course where tno in(select tno from teacher where depart="計算機系");
select * from score where cno in(select cno from course where tno in(select tno from teacher where depart="計算機系"));
#29、查詢選修編號為“3-105“課程且成績至少高於選修編號為“3-245”的同學的Cno、Sno和Degree,並按Degree從高到低次序排序。
select max(degree) from score where cno="3-245";
select * from score where cno="3-105" and degree>(select max(degree) from score where cno="3-245") order by degree desc;
#30、查詢選修編號為“3-105”且成績高於選修編號為“3-245”課程的同學的Cno、Sno和Degree.
select * from score where cno="3-105" and degree>(select max(degree) from score where cno="3-245");
#31、 查詢所有教師和同學的name、sex和birthday.
select sname,ssex,sbirthday from student 
union 
select tname,tsex,tbirthday from teacher;
#32、查詢所有“女”教師和“女”同學的name、sex和birthday.
select sname,ssex,sbirthday from student where ssex="女"
union 
select tname,tsex,tbirthday from teacher where tsex="女";
#33、 查詢成績比該課程平均成績低的同學的成績表。
select * from score group by cno having degree<avg(degree);
#34、 查詢所有任課教師的Tname和Depart.
select cno from score group by cno;
select tno from course where cno in(select cno from score group by cno);
select tname,depart from teacher where tno in(select tno from course where cno in(select cno from score group by cno));
#35 、 查詢所有未講課的教師的Tname和Depart. 
select tname,depart from teacher where tno not in(select tno from course where cno in(select cno from score group by cno));
#36、查詢至少有2名男生的班號。
select class from student where ssex="男" group by class having count(*)>1;
#37、查詢Student表中不姓“王”的同學記錄。
select * from student where sname not like"王%";
#38、查詢Student表中每個學生的姓名和年齡。
select sname,(2018-left(sbirthday,4)) as age from student;
#39、查詢Student表中最大和最小的Sbirthday日期值。
select max(sbirthday),min(sbirthday) from student;
#40、以班號和年齡從大到小的順序查詢Student表中的全部記錄。
select * from student order by class desc,(2018-left(sbirthday,4))  desc;
#41、查詢“男”教師及其所上的課程。
select tno from teacher where tsex="男";
select teacher.tname,course.cname from teacher,course where course.tno in(select tno from teacher where tsex="男") and course.tno= teacher.tno;
#42、查詢最高分同學的Sno、Cno和Degree列。
select max(degree) from score  ;
select * from score where degree=(select max(degree) from score);
#43、查詢和“李軍”同性別的所有同學的Sname.
select ssex from student where sname="李軍";
select sname from student where ssex=(select ssex from student where sname="李軍");
#44、查詢和“李軍”同性別並同班的同學Sname.
select class from student where sname="李軍";
select sname from student where ssex=(select ssex from student where sname="李軍") and class=(select class from student where sname="李軍");
#45、查詢所有選修“計算機導論”課程的“男”同學的成績表。
select cno from course where cname="計算機導論";
select sno from student where ssex="男";
select * from score where sno in(select sno from student where ssex="男") and cno in(select cno from course where cname="計算機導論")

數據庫表--增刪改查的操作實例