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@@ -9,12 +9,16 @@
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- 具体表象：用二维表（有行和列）组织数据。
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- 编程语言：结构化查询语言（SQL）。
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4. E-R图。
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+ - 实体 - 矩形框
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+ - 属性 - 椭圆框
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+ - 关系 - 菱形框
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+ - 重数 - 1:1 / 1:N / M:N
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5. 关系型数据库产品。
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- - Oracle
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- - DB2
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- - SQL Server
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- - MySQL
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- - SQLite
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+ - [Oracle](https://www.oracle.com/index.html)
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+ - [DB2](https://www.ibm.com/analytics/us/en/db2/)
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+ - [SQL Server](https://www.microsoft.com/en-us/sql-server/)
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+ - [MySQL](https://www.mysql.com/)
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+ - [SQLite](https://www.sqlite.org/index.html)
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### MySQL简介
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@@ -27,120 +31,164 @@
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```SQL
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- -- 如果存在SRS数据库就删除
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+ -- 创建数据库SRS
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drop database if exists SRS;
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-
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- -- 创建学生选课系统数据库SRS并指定默认字符集为UTF8
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create database SRS default charset utf8;
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- -- 切换至SRS数据库
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+ -- 切换到SRS
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use SRS;
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- -- 查看当前数据库中所有表
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- show tables;
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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 '学院编号',
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+ collname varchar(50) not null comment '学院名称',
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+ collmaster varchar(20) not null comment '院长姓名',
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+ collweb varchar(511) default '' comment '学院网站',
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+ primary key (collid)
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+ );
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+
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+ -- 添加唯一性约束
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+ alter table tb_college add constraint uni_college_collname unique (collname);
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+ -- alter table tb_college drop index uni_college_collname;
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- -- 创建学生表TbStudent
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- create table TbStudent
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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 integer not null,
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- stuname varchar(20) not null,
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- stusex bit default 1,
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- stubirth datetime not null,
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- stutel char(11),
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- stuaddr varchar(255),
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- stuphoto longblob,
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+ stuid int not null comment '学号',
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+ stuname varchar(20) not null comment '学生姓名',
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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 '所属学院编号',
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primary key (stuid)
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);
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- -- 修改学生表删除stutel列
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- alter table TbStudent drop column stutel;
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+ -- 添加外键约束
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+ alter table tb_student add constraint fk_student_collid foreign key (collid) references tb_college (collid);
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+
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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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+ teacherid int not null comment '教师工号',
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+ tname varchar(20) not null comment '教师姓名',
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+ ttitle varchar(10) default '' comment '职称',
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+ collid int not null comment '所属学院编号'
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+ );
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- -- 查看学生表结构
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- desc TbStudent;
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+ -- 添加主键约束
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+ alter table tb_teacher add constraint pk_teacher primary key (teacherid);
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- -- 如果表TbCourse已经存在就删除它
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- drop table if exists TbCourse;
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+ -- 添加外键约束
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+ alter table tb_teacher add constraint fk_teacher_collid foreign key (collid) references tb_college (collid);
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- -- 创建课程表TbCourse
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- create table TbCourse
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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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- cosid integer not null,
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- cosname varchar(50) not null,
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- coscredit tinyint not null,
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- cosintro varchar(255)
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+ courseid int not null comment '课程编号',
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+ cname varchar(50) not null comment '课程名称',
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+ ccredit tinyint not null comment '学分',
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+ tid int not null comment '教师工号',
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+ primary key (courseid)
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);
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- -- 给课程表设置主键约束
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- alter table TbCourse add constraint pk_course primary key (cosid);
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+ -- 添加外键约束
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+ alter table tb_course add constraint fk_course_tid foreign key (tid) references tb_teacher (teacherid);
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- -- 创建学生选课记录表TbSC
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- create table TbSC
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+ -- 创建学生选课表
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+ create table tb_score
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(
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- scid integer primary key auto_increment,
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- sid integer not null,
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- cid integer,
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- scdate datetime not null,
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- score float
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+ scid int not null auto_increment comment '选课编号',
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+ sid int not null comment '学号',
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+ cid int not null comment '课程编号',
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+ selectdate datetime comment '选课时间日期',
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+ score decimal(4,1) comment '考试成绩',
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+ primary key (scid)
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);
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- -- 给表TbSC添加外键约束
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- alter table TbSC add constraint fk_sid foreign key (sid) references TbStudent (stuid) on delete cascade on update cascade;
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- alter table TbSC add constraint fk_cid foreign key (cid) references TBCourse (cosid);
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+ -- 添加检查约束(MySQL中检查约束不生效)
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+ alter table tb_score add constraint ck_score_score check (score between 0 and 100);
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+
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+ -- 添加外键约束
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+ alter table tb_score add constraint fk_score_sid foreign key (sid) references tb_student (stuid);
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+ alter table tb_score add constraint fk_score_cid foreign key (cid) references tb_course (courseid);
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```
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2. DML
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```SQL
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- -- 添加学生记录
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- insert into TbStudent values (1001, '张三丰', default, '1978-1-1', '成都市一环路西二段17号', null);
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- insert into TbStudent (stuid, stuname, stubirth) values (1002, '郭靖', '1980-2-2');
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- insert into TbStudent (stuid, stuname, stusex, stubirth, stuaddr) values (1003, '黄蓉', 0, '1982-3-3', '成都市二环路南四段123号');
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- insert into TbStudent values (1004, '张无忌', 1, '1990-4-4', null, null);
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- insert into TbStudent values
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- (1005, '丘处机', 1, '1983-5-5', '北京市海淀区宝盛北里西区28号', null),
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- (1006, '王处一', 1, '1985-6-6', '深圳市宝安区宝安大道5010号', null),
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- (1007, '刘处玄', 1, '1987-7-7', '郑州市金水区纬五路21号', null),
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- (1008, '孙不二', 0, '1989-8-8', '武汉市光谷大道61号', null),
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- (1009, '平一指', 1, '1992-9-9', '西安市雁塔区高新六路52号', null),
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- (1010, '老不死', 1, '1993-10-10', '广州市天河区元岗路310号', null),
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- (1011, '王大锤', 0, '1994-11-11', null, null),
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- (1012, '隔壁老王', 1, '1995-12-12', null, null),
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- (1013, '郭啸天', 1, '1977-10-25', null, null);
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-
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- -- 删除学生记录
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- delete from TbStudent where stuid=1004;
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-
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- -- 更新学生记录
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- update TbStudent set stubirth='1980-12-12', stuaddr='上海市宝山区同济支路199号' where stuid=1002;
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-
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- -- 添加课程记录
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- insert into TbCourse values
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- (1111, 'C语言程序设计', 3, '大神级讲师授课需要抢座'),
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- (2222, 'Java程序设计', 3, null),
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- (3333, '数据库概论', 2, null),
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- (4444, '操作系统原理', 4, null);
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-
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- -- 添加学生选课记录
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- insert into TbSC values
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- (default, 1001, 1111, '2016-9-1', 95),
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- (default, 1002, 1111, '2016-9-1', 94),
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- (default, 1001, 2222, now(), null),
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- (default, 1001, 3333, '2017-3-1', 85),
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- (default, 1001, 4444, now(), null),
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- (default, 1002, 4444, now(), null),
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- (default, 1003, 2222, now(), null),
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- (default, 1003, 3333, now(), null),
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- (default, 1005, 2222, now(), null),
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- (default, 1006, 1111, now(), null),
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- (default, 1006, 2222, '2017-3-1', 80),
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- (default, 1006, 3333, now(), null),
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- (default, 1006, 4444, now(), null),
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- (default, 1007, 1111, '2016-9-1', null),
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- (default, 1007, 3333, now(), null),
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- (default, 1007, 4444, now(), null),
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- (default, 1008, 2222, now(), null),
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- (default, 1010, 1111, now(), null);
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+ -- 插入学院数据
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+ insert into tb_college
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+ (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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+
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+ -- 插入学生数据
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+ insert into tb_student
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+ (stuid, stuname, stusex, stubirth, stuaddr, collid) values
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+ (1001, '向问天', 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, '任盈盈', 0, '1989-12-3', '湖南长沙', 1),
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+ (1572, '余沧海', 1, '1993-7-19', '四川成都', 1),
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+ (1378, '岳灵珊', 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, '令狐冲', 1, '1988-6-30', '陕西咸阳', 2),
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+ (3011, '林震南', 1, '1985-12-12', '福建莆田', 3),
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+ (3755, '龙傲天', 1, '1993-1-25', '广东东莞', 3),
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+ (3923, '向天问', 0, '1985-4-17', '四川成都', 3),
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+ (2177, '隔壁老王', 1, '1989-11-27', '四川成都', 2);
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+
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+ -- 插入老师数据
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+ insert into tb_teacher
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+ (teacherid, tname, ttitle, 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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+
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+ -- 插入课程数据
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+ insert into tb_course
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+ (courseid, cname, ccredit, tid) 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', 3, 3366);
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+
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+ -- 插入选课数据
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+ insert into tb_score
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+ (sid, cid, selectdate, score) values
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+ (1001, 1111, now(), 95),
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+ (1001, 2222, now(), 87.5),
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+ (1001, 3333, now(), 100),
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+ (1001, 4444, now(), null),
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+ (1001, 6666, now(), 100),
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+ (1002, 1111, now(), 65),
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+ (1002, 5555, now(), 42),
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+ (1033, 1111, now(), 92.5),
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+ (1033, 4444, now(), 78),
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+ (1033, 5555, now(), 82.5),
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+ (1572, 1111, now(), 78),
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+ (1378, 1111, now(), 82),
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+ (1378, 7777, now(), 65.5),
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+ (2035, 7777, now(), 88),
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+ (2035, 9999, now(), 70),
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+ (3755, 1111, now(), 72.5),
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+ (3755, 8888, now(), 93),
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+ (3755, 9999, now(), null);
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+
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+ -- 删除数据
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+ delete from tb_student where stuid=2177;
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+
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+ -- 更新数据
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+ update tb_score set score=null where sid=1002 and cid=1111;
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```
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3. DQL
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@@ -148,90 +196,113 @@
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```SQL
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-- 查询所有学生信息
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- select * from TbStudent;
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+ select * from tb_student;
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+ select stuid, stuname, stusex, stubirth, stuaddr, collid
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+ 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 cosname as `课程名称`, coscredit as `学分` from TbCourse;
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+ select cname as 课程名称, ccredit as 学分 from tb_course;
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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 TbStudent where stusex=0;
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-
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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 as `姓名`, if(stusex, '男', '女') as `性别`, stubirth as `出生日期` from TbStudent where stubirth between '1980-1-1' and '1989-12-31';
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-
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- -- 查询姓王的学生姓名和性别(模糊)
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- select stuname, stusex from TbStudent where stuname like '王%';
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-
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- -- 查询姓郭名字总共两个字的学生的姓名(模糊)
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- select stuname from TbStudent where stuname like '郭_';
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-
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- -- 查询姓郭名字总共三个字的学生的姓名(模糊)
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- select stuname from TbStudent where stuname like '郭__';
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-
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- -- 查询名字中有王字的学生的姓名(模糊)
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- select stuname from TbStudent where stuname like '%王%';
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-
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- -- 查询没有录入家庭住址和照片的学生姓名(多条件筛选和空值处理)
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- select stuname from TbStudent where stuaddr is null and stuphoto is null;
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+ select stuname, stubirth from tb_student where stusex=0;
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+
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+ -- 查询所有80后女学生的姓名、性别(显示成'女')和出生日期(筛选)
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+ select stuname, '女' as stusex, stubirth from tb_student
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+ where stubirth between '1980-1-1' and '1989-12-31' and stusex=0;
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+
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+ -- 查询姓“林”的学生姓名和性别(模糊)
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+ select stuname, if(stusex, '男', '女') as stusex
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+ from tb_student where stuname like '林%';
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+
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+ -- 查询姓“张”名字总共两个字的老师的姓名和职称(模糊)
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+ select tname from tb_teacher where tname like '张_';
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+
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+ -- 查询姓“张”名字总共三个字的老师的姓名和职称(模糊)
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+ select tname, ttitle from tb_teacher where tname like '张__';
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+
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+ -- 查询名字中有“天”字的学生的姓名(模糊)
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+ select stuname from tb_student where stuname like '%天%';
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+
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+ -- 查询学生的籍贯
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+ select distinct stuaddr from tb_student
|
|
|
+ where stuaddr<>'' and 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)
|
|
|
+ select stuname, stubirth from tb_student
|
|
|
+ where stusex=1 order by stubirth asc;
|
|
|
+
|
|
|
+ -- 查询年龄最大/最小的学生的出生日期(聚合函数)
|
|
|
+ select min(stubirth) from tb_student;
|
|
|
+ select max(stubirth) from tb_student;
|
|
|
+ -- 查询学生/男学生/女学生的总人数
|
|
|
+ select count(stuid) from tb_student;
|
|
|
+ select count(stuid) from tb_student where stusex=1;
|
|
|
+ select count(stuid) from tb_student where stusex=0;
|
|
|
+ -- 查询1111课程的平均分/最低分/最高分/选课人数/考试人数
|
|
|
+ select avg(score) from tb_score where cid=1111;
|
|
|
+ select min(score) from tb_score where cid=1111;
|
|
|
+ select max(score) from tb_score where cid=1111;
|
|
|
+ select count(sid) from tb_score where cid=1111;
|
|
|
+ select count(score) from tb_score where cid=1111;
|
|
|
|
|
|
- -- 查询学生选课的所有日期(去重)
|
|
|
- select distinct scdate from TbSC;
|
|
|
+ -- 查询男女学生的人数(分组和聚合函数)
|
|
|
+ select if(stusex, '男', '女') as 性别, count(stusex) as 人数
|
|
|
+ from tb_student group by stusex order by 人数 desc;
|
|
|
|
|
|
- -- 查询学生的姓名和生日按年龄从大到小排列(排序)
|
|
|
- select stuname, stubirth from TbStudent order by stubirth;
|
|
|
+ -- 查询学号为1001的学生所有课程的总成绩(筛选和聚合函数)
|
|
|
+ select sum(score) as 总成绩 from tb_score where sid=1001;
|
|
|
|
|
|
- -- 查询所有录入了家庭住址的男学生的姓名、出生日期和家庭住址按年龄从小到大排列(多条件筛选和排序)
|
|
|
- select stuname, stubirth, stuaddr from TbStudent where stusex=1 and stuaddr is not null order by stubirth desc;
|
|
|
+ -- 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_score
|
|
|
+ where score is not null
|
|
|
+ group by sid
|
|
|
+ order by 平均分 desc;
|
|
|
|
|
|
- -- 查询年龄最大的学生的出生日期(聚合函数)
|
|
|
- select min(stubirth) from TbStudent;
|
|
|
+ -- 查询平均成绩大于等于80分的学生的学号和平均成绩(分组后的筛选)
|
|
|
+ select sid as 学号, avg(score) as 平均分
|
|
|
+ from tb_score
|
|
|
+ group by sid having 平均分>=80
|
|
|
+ order by 平均分 desc;
|
|
|
|
|
|
- -- 查询年龄最小的学生的出生日期(聚合函数)
|
|
|
- select max(stubirth) from TbStudent;
|
|
|
+ -- 查询年龄最大的学生的姓名(子查询)
|
|
|
+ select stuname from tb_student
|
|
|
+ where stubirth=(select min(stubirth) from tb_student);
|
|
|
+ select stuname from tb_student
|
|
|
+ where stubirth=(select max(stubirth) from tb_student);
|
|
|
|
|
|
- -- 查询男女学生的人数(分组和聚合函数)
|
|
|
- select if(stusex, '男', '女') as `性别`, count(stusex) as `人数` from TbStudent group by stusex;
|
|
|
+ -- 查询选了三门及以上的课程的学生姓名(子查询/分组条件/集合运算)
|
|
|
+ select stuname from tb_student where stuid in
|
|
|
+ (select sid from tb_score group by sid having count(sid)>=3);
|
|
|
|
|
|
- -- 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) as `平均成绩` from TbSC where cid=1111;
|
|
|
+ -- 查询课程名称、学分、授课老师的名字和职称
|
|
|
+ select cname, ccredit, tname, ttitle
|
|
|
+ from tb_course, tb_teacher
|
|
|
+ where tid=teacherid;
|
|
|
|
|
|
- -- 查询学号为1001的学生所有课程的总成绩(筛选和聚合函数)
|
|
|
- select sum(score) as `总成绩` from TbSC where sid=1001;
|
|
|
+ select cname, ccredit, tname, ttitle
|
|
|
+ from tb_course inner join tb_teacher
|
|
|
+ on tid=teacherid;
|
|
|
|
|
|
- -- 查询每个学生的学号和平均成绩, null值处理成0(分组和聚合函数)
|
|
|
- select sid as `学号`, ifnull(avg(score), 0) as `平均成绩` from TbSC group by sid;
|
|
|
+ -- 查询学生姓名和所在学院名称
|
|
|
+ select stuname, collname
|
|
|
+ from tb_student t1, tb_college t2
|
|
|
+ where t1.collid=t2.collid;
|
|
|
|
|
|
- -- 查询平均成绩大于等于90分的学生的学号和平均成绩
|
|
|
- select sid as `学号`, avg(score) as `平均成绩` from TbSC group by sid having avg(score)>=90;
|
|
|
+ select stuname, collname from tb_student t1
|
|
|
+ inner join tb_college t2 on t1.collid=t2.collid;
|
|
|
|
|
|
- -- 查询年龄最大的学生的姓名(子查询)
|
|
|
- select stuname from TbStudent where stubirth=(select min(stubirth) from TbStudent);
|
|
|
+ -- 查询学生姓名、课程名称以及考试成绩
|
|
|
|
|
|
- -- 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)
|
|
|
- select stuname from TbStudent where stuid in
|
|
|
- (select sid from TbSC group by sid having count(sid)>2);
|
|
|
|
|
|
-- 查询选课学生的姓名和平均成绩(子查询和连接查询)
|
|
|
- -- 写法1:
|
|
|
- select stuname, avgscore from TbStudent t1 inner join
|
|
|
- (select sid, avg(score) as avgscore from TbSC where score is not null group by sid) t2 on t1.stuid=t2.sid;
|
|
|
- -- 写法2:
|
|
|
- select stuname, avgscore from TbStudent t1,
|
|
|
- (select sid, avg(score) as avgscore from TbSC where score is not null group by sid) t2 where t1.stuid=t2.sid;
|
|
|
+
|
|
|
|
|
|
-- 查询学生姓名、所选课程名称和成绩(连接查询)
|
|
|
- -- 写法1:
|
|
|
- select stuname, cosname, score from
|
|
|
- TbStudent t1, TbCourse t2, TbSC t3
|
|
|
- where t1.stuid=t3.sid and t2.cosid=t3.cid and t3.score is not null;
|
|
|
- -- 写法2:
|
|
|
- select stuname, cosname, score from TbStudent t1 inner join TbCourse t2
|
|
|
- inner join (select sid, cid, score from TbSC where score is not null) t3
|
|
|
- on t1.stuid=t3.sid and t2.cosid=t3.cid;
|
|
|
+
|
|
|
|
|
|
-- 查询每个学生的姓名和选课数量(左外连接和子查询)
|
|
|
- select stuname as `姓名`, ifnull(coscount, 0) as `选课数` from TbStudent t1
|
|
|
- left outer join (select sid, count(sid) as coscount from TbSC group by sid) t2 on t1.stuid=t2.sid;
|
|
|
+
|
|
|
```
|
|
|
|
|
|
4. DCL
|
|
|
@@ -248,6 +319,22 @@
|
|
|
revoke insert, delete, update on SRS.* from 'hellokitty'@'localhost';
|
|
|
```
|
|
|
|
|
|
+### 相关知识
|
|
|
+
|
|
|
+#### 范式理论
|
|
|
+
|
|
|
+#### 数据完整性
|
|
|
+
|
|
|
+1. 实体完整性 - 每个实体都是独一无二的
|
|
|
+ - 主键 / 唯一约束 / 唯一索引
|
|
|
+2. 引用完整性（参照完整性）
|
|
|
+ - 外键
|
|
|
+3. 域完整性 - 数据是有效的
|
|
|
+ - 数据类型
|
|
|
+ - 非空约束
|
|
|
+ - 默认值约束
|
|
|
+ - 检查约束
|
|
|
+
|
|
|
### Python数据库编程
|
|
|
|
|
|
1. MySQLdb
|
jackfrued