– 如果存在名为school的数据库就删除它
drop database if exists school;

– 创建名为school的数据库并设置默认的字符集和排序方式
create database school default charset utf8;

– 切换到school数据库上下文环境
use school;

– 创建学院表
create table tb_college
(
collid int auto_increment comment ‘编号’,
collname varchar(50) not null comment ‘名称’,
collintro varchar(500) default ‘’ comment ‘介绍’,
primary key (collid)
);

– 创建学生表
create table tb_student
(
stuid int not null comment ‘学号’,
stuname varchar(20) not null comment ‘姓名’,
stusex boolean default 1 comment ‘性别’,
stubirth date not null comment ‘出生日期’,
stuaddr varchar(255) default ‘’ comment ‘籍贯’,
collid int not null comment ‘所属学院’,
primary key (stuid),
foreign key (collid) references tb_college (collid)
);

– 创建教师表
create table tb_teacher
(
teaid int not null comment ‘工号’,
teaname varchar(20) not null comment ‘姓名’,
teatitle varchar(10) default ‘助教’ comment ‘职称’,
collid int not null comment ‘所属学院’,
primary key (teaid),
foreign key (collid) references tb_college (collid)
);

– 创建课程表
create table tb_course
(
couid int not null comment ‘编号’,
couname varchar(50) not null comment ‘名称’,
coucredit int not null comment ‘学分’,
teaid int not null comment ‘授课老师’,
primary key (couid),
foreign key (teaid) references tb_teacher (teaid)
);

– 创建选课记录表
create table tb_record
(
recid int auto_increment comment ‘选课记录编号’,
sid int not null comment ‘选课学生’,
cid int not null comment ‘所选课程’,
seldate date not null comment ‘选课时间日期’,
score decimal(4,1) comment ‘考试成绩’,
primary key (recid),
foreign key (sid) references tb_student (stuid),
foreign key (cid) references tb_course (couid),
unique (sid, cid)
);

– 插入学院数据
insert into tb_college (collname, collintro) values
(‘计算机学院’, ‘创建于1956年是我国首批建立计算机专业。学院现有计算机科学与技术一级学科和网络空间安全一级学科博士学位授予权，其中计算机科学与技术一级学科具有博士后流动站。计算机科学与技术一级学科在2017年全国第四轮学科评估中评为A；2019 U.S.News全球计算机学科排名26名；ESI学科排名0.945‰，进入全球前1‰，位列第43位。’),
(‘外国语学院’, ‘1998年浙江大学、杭州大学、浙江农业大学、浙江医科大学四校合并，成立新的浙江大学。1999年原浙江大学外语系、原杭州大学外国语学院、原杭州大学大外部、原浙江农业大学公外部、原浙江医科大学外语教学部合并，成立浙江大学外国语学院。2003年学院更名为浙江大学外国语言文化与国际交流学院。’),
(‘经济管理学院’, ‘四川大学经济学院历史悠久、传承厚重，其前身是创办于1905年的四川大学经济科,距今已有100多年的历史。已故著名经济学家彭迪先、张与九、蒋学模、胡寄窗、陶大镛、胡代光，以及当代著名学者刘诗白等曾先后在此任教或学习。在长期的办学过程中，学院坚持以马克思主义的立场、观点、方法为指导，围绕建设世界一流经济学院的奋斗目标，做实“两个伟大”深度融合，不断提高党的建设质量与科学推进一流事业深度融合。’);

– 插入学生数据
insert into tb_student (stuid, stuname, stusex, stubirth, stuaddr, collid) values --datediff(当前时间,出生年月)
(1001, ‘杨逍’, 1, ‘1990-3-4’, ‘四川成都’, 1),
(1002, ‘任我行’, 1, ‘1992-2-2’, ‘湖南长沙’, 1),
(1033, ‘王语嫣’, 0, ‘1989-12-3’, ‘四川成都’, 1),
(1572, ‘岳不群’, 1, ‘1993-7-19’, ‘陕西咸阳’, 1),
(1378, ‘纪嫣然’, 0, ‘1995-8-12’, ‘四川绵阳’, 1),
(1954, ‘林平之’, 1, ‘1994-9-20’, ‘福建莆田’, 1),
(2035, ‘东方不败’, 1, ‘1988-6-30’, null, 2),
(3011, ‘林震南’, 1, ‘1985-12-12’, ‘福建莆田’, 3),
(3755, ‘项少龙’, 1, ‘1993-1-25’, null, 3),
(3923, ‘杨不悔’, 0, ‘1985-4-17’, ‘四川成都’, 3),
(4040, ‘隔壁老王’, 1, ‘1989-1-1’, ‘四川成都’, 2);

– 删除学生数据
delete from tb_student where stuid=4040;

– 更新学生数据
update tb_student set stuname=‘杨过’, stuaddr=‘湖南长沙’ where stuid=1001;

– 插入老师数据
insert into tb_teacher (teaid, teaname, teatitle, collid) values
(1122, ‘张三丰’, ‘教授’, 1),
(1133, ‘宋远桥’, ‘副教授’, 1),
(1144, ‘杨逍’, ‘副教授’, 1),
(2255, ‘范遥’, ‘副教授’, 2),
(3366, ‘韦一笑’, ‘讲师’, 3);

– 插入课程数据
insert into tb_course (couid, couname, coucredit, teaid) values
(1111, ‘Python程序设计’, 3, 1122),
(2222, ‘Web前端开发’, 2, 1122),
(3333, ‘操作系统’, 4, 1122),
(4444, ‘计算机网络’, 2, 1133),
(5555, ‘编译原理’, 4, 1144),
(6666, ‘算法和数据结构’, 3, 1144),
(7777, ‘经贸法语’, 3, 2255),
(8888, ‘成本会计’, 2, 3366),
(9999, ‘审计学’, 3, 3366);

– 插入选课数据
insert into tb_record (sid, cid, seldate, score) values
(1001, 1111, ‘2017-09-01’, 95),
(1001, 2222, ‘2017-09-01’, 87.5),
(1001, 3333, ‘2017-09-01’, 100),
(1001, 4444, ‘2018-09-03’, null),
(1001, 6666, ‘2017-09-02’, 100),
(1002, 1111, ‘2017-09-03’, 65),
(1002, 5555, ‘2017-09-01’, 42),
(1033, 1111, ‘2017-09-03’, 92.5),
(1033, 4444, ‘2017-09-01’, 78),
(1033, 5555, ‘2017-09-01’, 82.5),
(1572, 1111, ‘2017-09-02’, 78),
(1378, 1111, ‘2017-09-05’, 82),
(1378, 7777, ‘2017-09-02’, 65.5),
(2035, 7777, ‘2018-09-03’, 88),
(2035, 9999, curdate(), null),
(3755, 1111, curdate(), null),
(3755, 8888, curdate(), null),
(3755, 9999, ‘2017-09-01’, 92);

– 查询所有学生信息
SELECT * FROM tb_student;
– 查询所有课程名称及学分(投影和别名)
SELECT couname as 课程名称,coucredit as 学分 FROM tb_course;
– 查询所有学生的姓名和性别(条件运算)
SELECT stuname as 姓名,stusex as 性别 from tb_student;
SELECT stuname as 姓名,case stusex WHEN 1 THEN ‘男’ else ‘女’ end as ‘性别’ from tb_student;
– 查询所有女学生的姓名和出生日期(筛选)
SELECT stuname as 姓名,stubirth as ‘出生日期’ from tb_student where stusex=0;
– 查询所有80后学生的姓名、性别和出生日期(筛选)
SELECT stuname as 姓名,stusex as 性别,stubirth as ‘出生日期’ from tb_student where stubirth>=‘1980-1-1’ and stubirth <= ‘1989-12-31’;
SELECT stuname as 姓名,stusex as 性别,stubirth as ‘出生日期’ from tb_student where stubirth BETWEEN ‘1980-1-1’ and ‘1989-12-31’ ;

– 查询姓"杨"的学生姓名和性别(模糊)杨_ 一个字
SELECT stuname as 姓名,stusex as 性别 from tb_student where stuname like ‘杨%’;

– 查询姓"杨"名字两个字的学生姓名和性别(模糊)
SELECT stuname as 姓名,stusex as 性别 from tb_student where stuname like ‘杨_’;

– 查询姓"杨"名字三个字的学生姓名和性别(模糊)杨__
SELECT stuname as 姓名,stusex as 性别 from tb_student where stuname like ‘杨__’;

– 查询名字中有"不"字或"嫣"字的学生的姓名(模糊)
SELECT stuname as 姓名,stusex as 性别 from tb_student where stuname like ‘%不%’ or stuname like ‘%嫣%’;
– 查询没有录入家庭住址的学生姓名(空值)
SELECT stuname as 学生姓名 FROM tb_student where stuaddr is NULL;
– 查询录入了家庭住址的学生姓名(空值)
SELECT stuname as 学生姓名 FROM tb_student where stuaddr is NOT NULL;

– 查询学生选课的所有日期(去重)
SELECT DISTINCT seldate FROM tb_record;
– 查询学生的家庭住址(去重)
SELECT DISTINCT stuaddr as ‘学生地址’ from tb_student where stuaddr is not null;
– 查询男学生的姓名和生日按年龄从大到小排列(排序) order by desc
SELECT stuname as 姓名,DATEDIFF(CURDATE(),stubirth) DIV 365 as 年龄 from tb_student where stusex=1 ORDER BY stubirth DESC;
SELECT stuname as 姓名,(year(now())-year(stubirth)) as 年龄 from tb_student where stusex=1 ORDER BY stubirth DESC;
– 查询年龄最大的学生的出生日期(聚合函数) min()
SELECT stuname,stubirth from tb_student where stubirth in(SELECT min(stubirth) from tb_student);

– 查询年龄最小的学生的出生日期(聚合函数)min()
SELECT stuname,stubirth from tb_student where stubirth in(SELECT max(stubirth) from tb_student);

– 查询男女学生的人数(分组和聚合函数)
SELECT COUNT(*) as 人数 ,stusex as 性别 from tb_student group by stusex;
– 查询课程编号为1111的课程的平均成绩(筛选和聚合函数)
SELECT avg(score) from tb_record where cid=1111;
– 查询学号为1001的学生所有课程的平均分(筛选和聚合函数)
SELECT sid as 学号,AVG(score) as 平均分 FROM tb_record where sid=1001;
– 查询每个学生的学号和平均成绩(分组和聚合函数)
SELECT sid as 学号,AVG(score) as 平均分 FROM tb_record GROUP BY sid;
– 查询平均成绩大于等于90分的学生的学号和平均成绩
– 分组以前的筛选使用where子句 / 分组以后的筛选使用having子句
SELECT sid as 学号,AVG(score) as 平均分 FROM tb_record GROUP BY sid HAVING 平均分>90;

– 查询年龄最大的学生的姓名(子查询/嵌套的查询)
SELECT MIN(stubirth),stuname from tb_student;
SELECT stuname from tb_student where stubirth in (SELECT min(stubirth) from tb_student);
– 查询年龄最大的学生姓名和年龄(子查询+运算)
SELECT stuname,DATEDIFF(CURDATE(),stubirth) DIV 365 as 年龄 from tb_student where stubirth in (SELECT min(stubirth) from tb_student);
– 查询选了两门以上的课程的学生姓名(子查询/分组条件/集合运算)
– 选课
SELECT sid from tb_record GROUP BY sid HAVING COUNT(sid)>2;
SELECT stuname from tb_student WHERE stuid in (SELECT sid from tb_record GROUP BY sid HAVING COUNT(sid)>2);

– 查询学生姓名、课程名称以及成绩(连接查询)学生 表 选课表 课程表
SELECT stuname,couname,score from tb_student t1,tb_record t2,tb_course t3 where stuid=sid and cid=couid and score is not null;
SELECT stuname,couname,IFNULL(score,‘没成绩’) from tb_student t1,tb_record t2,tb_course t3 where stuid=sid and cid=couid ORDER BY score desc;

– 查询学生姓名、课程名称以及成绩按成绩从高到低查询第11-15条记录(内连接+分页)
– limit 0,10 必须知道用户相看第几页
SELECT stuname,couname,IFNULL(score,‘没成绩’) from tb_student t1,tb_record t2,tb_course t3 where stuid=sid and cid=couid ORDER BY score DESC LIMIT 5 OFFSET 10;
SELECT stuname,couname,IFNULL(score,‘没成绩’) from tb_student INNER JOIN tb_record on stuid=sid INNER JOIN tb_course on couid=cid ORDER BY score desc limit 5 OFFSET 10;

– 查询选课学生的姓名和平均成绩(子查询和连接查询) 学生表 选课表
SELECT stuname,平均成绩 from tb_student,(SELECT sid,AVG(score) as 平均成绩 from tb_record GROUP BY sid)temp where stuid=sid;
SELECT stuname,平均成绩 from tb_student INNER JOIN (SELECT sid,AVG(score) as 平均成绩 from tb_record GROUP BY sid)temp on stuid=sid;

– 查询每个学生的姓名和选课数量(左外连接和子查询)
SELECT stuname from tb_student;
SELECT sid,count(sid) as total from tb_record GROUP BY sid;
SELECT stuname,IFNULL(total,0) FROM tb_student LEFT JOIN (SELECT sid,count(sid) as total from tb_record GROUP BY sid)temp on stuid=sid;