243 lines
9.6 KiB
SQL
243 lines
9.6 KiB
SQL
-- 如果存在名为school的数据库就删除它
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drop database if exists school;
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-- 创建名为school的数据库并设置默认的字符集和排序方式
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create database school default charset utf8 collate utf8_bin;
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-- 切换到school数据库上下文环境
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use school;
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-- 创建学院表
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create table tb_college
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(
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collid int not null auto_increment comment '编号',
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collname varchar(50) not null comment '名称',
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collmaster varchar(20) not null comment '院长',
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collweb varchar(511) default '' comment '网站',
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primary key (collid)
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);
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-- 创建学生表
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create table tb_student
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(
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stuid int not null comment '学号',
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stuname varchar(20) not null comment '姓名',
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stusex bit default 1 comment '性别',
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stubirth date not null comment '出生日期',
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stuaddr varchar(255) default '' comment '籍贯',
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collid int not null comment '所属学院',
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primary key (stuid),
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foreign key (collid) references tb_college (collid)
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);
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-- alter table tb_student add constraint fk_student_collid foreign key (collid) references tb_college (collid);
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-- 创建教师表
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create table tb_teacher
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(
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teaid int not null comment '工号',
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teaname varchar(20) not null comment '姓名',
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teatitle varchar(10) default '助教' comment '职称',
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collid int not null comment '所属学院',
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primary key (teaid),
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foreign key (collid) references tb_college (collid)
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);
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-- 创建课程表
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create table tb_course
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(
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couid int not null comment '编号',
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couname varchar(50) not null comment '名称',
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coucredit int not null comment '学分',
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teaid int not null comment '授课老师',
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primary key (couid),
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foreign key (teaid) references tb_teacher (teaid)
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);
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-- 创建选课记录表
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create table tb_score
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(
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scid int auto_increment comment '选课记录编号',
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stuid int not null comment '选课学生',
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couid int not null comment '所选课程',
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scdate datetime comment '选课时间日期',
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scmark decimal(4,1) comment '考试成绩',
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primary key (scid),
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foreign key (stuid) references tb_student (stuid),
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foreign key (couid) references tb_course (couid)
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);
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-- 添加唯一性约束（一个学生选某个课程只能选一次）
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alter table tb_score add constraint uni_score_stuid_couid unique (stuid, couid);
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-- 插入学院数据
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insert into tb_college (collname, collmaster, collweb) values
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('计算机学院', '左冷禅', 'http://www.abc.com'),
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('外国语学院', '岳不群', 'http://www.xyz.com'),
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('经济管理学院', '风清扬', 'http://www.foo.com');
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-- 插入学生数据
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insert into tb_student (stuid, stuname, stusex, stubirth, stuaddr, collid) values
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(1001, '杨逍', 1, '1990-3-4', '四川成都', 1),
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(1002, '任我行', 1, '1992-2-2', '湖南长沙', 1),
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(1033, '王语嫣', 0, '1989-12-3', '四川成都', 1),
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(1572, '岳不群', 1, '1993-7-19', '陕西咸阳', 1),
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(1378, '纪嫣然', 0, '1995-8-12', '四川绵阳', 1),
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(1954, '林平之', 1, '1994-9-20', '福建莆田', 1),
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(2035, '东方不败', 1, '1988-6-30', null, 2),
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(3011, '林震南', 1, '1985-12-12', '福建莆田', 3),
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(3755, '项少龙', 1, '1993-1-25', null, 3),
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(3923, '杨不悔', 0, '1985-4-17', '四川成都', 3);
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-- 插入老师数据
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insert into tb_teacher (teaid, teaname, teatitle, collid) values
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(1122, '张三丰', '教授', 1),
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(1133, '宋远桥', '副教授', 1),
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(1144, '杨逍', '副教授', 1),
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(2255, '范遥', '副教授', 2),
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(3366, '韦一笑', '讲师', 3);
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-- 插入课程数据
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insert into tb_course (couid, couname, coucredit, teaid) values
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(1111, 'Python程序设计', 3, 1122),
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(2222, 'Web前端开发', 2, 1122),
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(3333, '操作系统', 4, 1122),
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(4444, '计算机网络', 2, 1133),
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(5555, '编译原理', 4, 1144),
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(6666, '算法和数据结构', 3, 1144),
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(7777, '经贸法语', 3, 2255),
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(8888, '成本会计', 2, 3366),
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(9999, '审计学', 3, 3366);
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-- 插入选课数据
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insert into tb_score (stuid, couid, scdate, scmark) values
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(1001, 1111, '2017-09-01', 95),
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(1001, 2222, '2017-09-01', 87.5),
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(1001, 3333, '2017-09-01', 100),
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(1001, 4444, '2018-09-03', null),
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(1001, 6666, '2017-09-02', 100),
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(1002, 1111, '2017-09-03', 65),
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(1002, 5555, '2017-09-01', 42),
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(1033, 1111, '2017-09-03', 92.5),
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(1033, 4444, '2017-09-01', 78),
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(1033, 5555, '2017-09-01', 82.5),
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(1572, 1111, '2017-09-02', 78),
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(1378, 1111, '2017-09-05', 82),
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(1378, 7777, '2017-09-02', 65.5),
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(2035, 7777, '2018-09-03', 88),
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(2035, 9999, curdate(), null),
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(3755, 1111, date(now()), null),
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(3755, 8888, date(now()), null),
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(3755, 9999, '2017-09-01', 92);
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-- 查询所有学生信息
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select * from tb_student;
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-- 查询所有课程名称及学分(投影和别名)
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select couname, coucredit from tb_course;
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select couname as 课程名称, coucredit as 学分 from tb_course;
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select stuname as 姓名, case stusex when 1 then '男' else '女' end as 性别 from tb_student;
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select stuname as 姓名, if(stusex, '男', '女') as 性别 from tb_student;
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-- 查询所有女学生的姓名和出生日期(筛选)
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select stuname, stubirth from tb_student where stusex=0;
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-- 查询所有80后学生的姓名、性别和出生日期(筛选)
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select stuname, stusex, stubirth from tb_student where stubirth>='1980-1-1' and stubirth<='1989-12-31';
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select stuname, stusex, stubirth from tb_student where stubirth between '1980-1-1' and '1989-12-31';
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-- 查询姓"杨"的学生姓名和性别(模糊)
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select stuname, stusex from tb_student where stuname like '杨%';
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-- 查询姓"杨"名字两个字的学生姓名和性别(模糊)
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select stuname, stusex from tb_student where stuname like '杨_';
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-- 查询姓"杨"名字三个字的学生姓名和性别(模糊)
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select stuname, stusex from tb_student where stuname like '杨__';
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-- 查询名字中有"不"字或"嫣"字的学生的姓名(模糊)
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select stuname, stusex from tb_student where stuname like '%不%' or stuname like '%嫣%';
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-- 查询没有录入家庭住址的学生姓名(空值)
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select stuname from tb_student where stuaddr is null;
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-- 查询录入了家庭住址的学生姓名(空值)
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select stuname from tb_student where stuaddr is not null;
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-- 查询学生选课的所有日期(去重)
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select distinct scdate from tb_score;
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-- 查询学生的家庭住址(去重)
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select distinct stuaddr from tb_student where stuaddr is not null;
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-- 查询男学生的姓名和生日按年龄从大到小排列(排序)
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-- asc - ascending - 升序（从小到大）
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-- desc - descending - 降序（从大到小）
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select stuname as 姓名, year(now())-year(stubirth) as 年龄 from tb_student where stusex=1 order by 年龄 desc;
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-- 聚合函数：max / min / count / sum / avg
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-- 查询年龄最大的学生的出生日期(聚合函数)
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select min(stubirth) from tb_student;
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-- 查询年龄最小的学生的出生日期(聚合函数)
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select max(stubirth) from tb_student;
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-- 查询男女学生的人数(分组和聚合函数)
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select count(stuid) from tb_student;
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select stusex, count(*) from tb_student group by stusex;
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select stusex, min(stubirth) from tb_student group by stusex;
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-- 查询课程编号为1111的课程的平均成绩(筛选和聚合函数)
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select avg(scmark) from tb_score where couid=1111;
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select min(scmark) from tb_score where couid=1111;
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select count(scid) from tb_score where couid=1111;
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select count(scmark) from tb_score where couid=1111;
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-- 查询学号为1001的学生所有课程的平均分(筛选和聚合函数)
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select avg(scmark) from tb_score where stuid=1001;
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-- 查询每个学生的学号和平均成绩(分组和聚合函数)
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select stuid as 学号, avg(scmark) as 平均分 from tb_score group by stuid;
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-- 查询平均成绩大于等于90分的学生的学号和平均成绩
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-- 分组以前的筛选使用where子句
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-- 分组以后的筛选使用having子句
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select stuid as 学号, avg(scmark) as 平均分 from tb_score group by stuid having 平均分>=90;
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-- 查询年龄最大的学生的姓名(子查询/嵌套的查询)
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select stuname from tb_student where stubirth=(
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select min(stubirth) from tb_student
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);
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-- 查询年龄最大的学生姓名和年龄(子查询+运算)
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select stuname as 姓名, year(now())-year(stubirth) as 年龄 from tb_student where stubirth=(
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select min(stubirth) from tb_student
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);
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-- 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)
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select stuname from tb_student where stuid in (
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select stuid from tb_score group by stuid having count(stuid)>2
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)
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-- 查询学生姓名、课程名称以及成绩(连接查询)
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select stuname, couname, scmark from tb_student t1, tb_course t2, tb_score t3 where t1.stuid=t3.stuid and t2.couid=t3.couid and scmark is not null;
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select stuname, couname, scmark from tb_student t1 inner join tb_score t3 on t1.stuid=t3.stuid inner join tb_course t2 on t2.couid=t3.couid where scmark is not null order by scmark desc limit 5 offset 10;
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select stuname, couname, scmark from tb_student t1 inner join tb_score t3 on t1.stuid=t3.stuid inner join tb_course t2 on t2.couid=t3.couid where scmark is not null order by scmark desc limit 10, 5;
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-- 单表：65535TB
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-- 单列：4G - LONGBLOB (Binary Large OBject) / LONGTEXT
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-- 查询选课学生的姓名和平均成绩(子查询和连接查询)
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select stuname, avgmark from tb_student t1, (select stuid, avg(scmark) as avgmark from tb_score group by stuid) t2 where t1.stuid=t2.stuid;
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select stuname, avgmark from tb_student t1 inner join
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(select stuid, avg(scmark) as avgmark from tb_score group by stuid) t2 on t1.stuid=t2.stuid;
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-- 内连接（inner join）：只有满足连接条件的记录才会被查出来
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-- 外连接（outer join）：左外连接 / 右外连接 / 全外连接
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-- left outer join / right outer join / full outer join
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-- 查询每个学生的姓名和选课数量(左外连接和子查询)
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select stuname, ifnull(total, 0) from tb_student t1 left outer join (select stuid, count(stuid) as total from tb_score group by stuid) t2 on t1.stuid=t2.stuid;
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