项目3创建与维护MySQL数据表

原创已于 2022-03-17 12:43:30 修改 · 526 阅读

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#mysql #数据库 #database

于 2022-03-04 21:56:33 首次发布

本文详细介绍了如何使用MySQL进行数据库的创建与维护，包括查看数据库、选择数据库、创建和修改表结构、以及备份与恢复。此外，还展示了如何向表中新增数据，如指定字段插入、所有字段插入、批量插入等，并通过实例演示了表的约束，如主键、唯一性、默认值和外键。最后，讲解了数据库的备份与恢复操作，包括全库备份、单库备份和恢复。

目录

创建与维护

表的约束

新增数据

备份与恢复

创建与维护

首先我们打开命令提示符登录MySQL

输入 show databases; 查看一下所有数据库

随后输入 use 表名，使用数据库

出现 Database changed 就表示成功了

之后输入create table 表名（）括号中输入你的字段与数据类型，

可以使用comment"" 在数据类型后增加注释信息

出现Query OK, 0 rows affected (0.02 sec) 就代表成功了

我们查看一下表的创建信息

之后我们可以尝试修改表名

我们将数据表 stt 改为 std

我们查看一下数据表信息

可以看到表名已经被修改了

随后我们可以修改字段名和数据类型

输入 alter table 表名 change 旧name 新name 字段char(5); 就可以修改表的字段信息

添加字段

输入 alter table 表名 add （新字段）即可添加新字段

在这段代码后加一个first便可将改字段添加到第一个

例如：

输入 alter table 表名 add （新字段）新数据类型后加 after 便可将此字段添加到任意字段后

例如：

修改字段位置

输入

alter table 表名 modify 待修改字段名数据类型 after 字段名:

例如：

删除字段
alter table 表名drop 字段名;

例如：

我们查看一下数据表

最后删除数据表输入drop table 表名;

表的约束

创建教师表

输入 create table teacher(
-> no char(4) comment"教师号" primary key,
-> name varchar(10) comment"教师姓名" not null,
-> prof varchar(20) comment"职称" not null default"助教",
-> sal int(2) comment"工资"not null,
-> comm smallint(2) comment"岗位津贴"
-> );

查看

创建学生表 student

create table student(
-> no char(4) comment"学生号" primary key,
-> name varchar(10) comment"学生姓名" not null,
-> age tinyint(1) comment"年龄" not null,
-> dept varchar(20) comment"系名" not null default"计算机系"
-> );

查看

创建课程表

create table course(
-> no char(4) comment"课程号" primary key,
-> name varchar(20) comment"课程名" not null unique,
-> class_hours int(2) comment"课时数" default"45"
-> );
Query OK, 0 rows affected, 1 warning (0.03 sec)

查看

创建授课表

输入

create table school_teaching(
-> id int(4) comment"序号" primary key auto_increment,
-> course_no char(4) comment"课程号" not null,
-> teacher_no char(4) comment"教师号" not null,
-> week int(2) comment "周数" default"15",
-> class_num varchar(10) comment"教师号",
-> constraint fk_course_no foreign key (course_no) references course(no),
-> constraint fk_teacher_no foreign key (teacher_no) references teacher(no)
-> );

查看

创建成绩表

输入 create table chengweiqiang_grade(
-> course_no char(4) comment"课程号" not null,
-> student_no char(4) comment"学生号" not null,
-> score float comment"成绩" not null default"60",
-> primary key(course_no,student_no)
-> );

新增数据

如下表新增数据：

指定字段插入数据时若插入值为空时，无需指定该字段名，

教师表 teacher
1. 指定字段插入数据

教师号	教师姓名	职称	工资	岗位津贴
T1	Anne	Professor	5000	2000
T2	Adam		2000
T3	Alan	Associate Professor	4000	1500
T4	Ben		2000	500
T5	Bob	Lecturer	3000

输入： insert into teacher (no,name,prof,sal,comm)
-> values ("T1","Anne","professor","5000","2000"),
-> ("T2","Adam","0","2000","0"),
-> ("T3","Alan","Associate professor","4000","1500"),
-> ("T4","Ben","0","2000","500"),
-> ("T5","Bob","Lecturer","3000","0");
Query OK, 5 rows affected (0.01 sec)

查看：

1. 所有字段插入数据

教师号	教师姓名	职称	工资	岗位津贴
T6	Brant	Lecturer	3000
T7	Bruce	Teaching Assistant	2000	500

输入代码：insert into teacher values ("T6","brant","lecturer","3000","1500"),("T7","bruce","teaching Assistant","3000","1000");
Query OK, 2 rows affected (0.01 sec)

查看

1. 所有字段批量插入数据

教师号	教师姓名	职称	工资	岗位津贴
T8	Cary	Associate Professor	4000	1500
T9	Chris		2000
T10	Daniel	Lecturer	3000	1000

输入

insert into teacher values
-> ("T8","cary","Associate professor","4000","1500"),
-> ("T9","chris","0","2000","0"),
-> ("T10","daniel","Lecturer","3000","1000");
Query OK, 3 rows affected (0.01 sec)

查看

1. 指定字段批量插入数据

教师号	教师姓名	职称	工资	岗位津贴
T11	David	Associate Professor	4000
T12	Edward	Teaching Assistant	2000
T13	Eric	Professor	5000

输入

insert into teacher (no,name,prof,sal,comm)
-> values ("T11","david","Associate professor","4000","0"),
-> ("T12","edward","teaching Assistant","2000","0"),
-> ("T13","eric","professor","5000","0");
Query OK, 3 rows affected (0.01 sec)

查看

1. 查看教师表中教师号、教师姓名、职称、工资字段数据

课程表 course
1. 指定字段插入数据

课程号	课程名	课时数
C1	Mysql	80
C2	cloud computing

输入

insert into course(no,name,class_hours) values
-> ("c1","mysql","80"),
-> ("c2","cloud computing","0");
Query OK, 2 rows affected (0.01 sec)

查看

1. 所有字段插入数据

课程号	课程名	课时数
C3	Professional English	30
C4	Network foundation

输入

insert into course values
-> ("c3","Professional English","30"),
-> ("c4","Network foundation","0");
Query OK, 2 rows affected (0.01 sec)

查看

1. 所有字段批量插入数据

课程号	课程名	课时数
C5	Flash	50
C6	marketing

输入

insert into course values
-> ("c5","flash","50"),
-> ("c6","marketing","0");

查看

1. 指定字段批量插入数据

课程号	课程名	课时数
C7	Situation and Policy
C8	Patriotic education

输入

insert into course(no,name,class_hours) values
-> ("c7","Situation and Policy","0"),
-> ("c8","Patriotic education","0");

输入

查看

1. 查看课程表中课程号、课程名、课时数字段数据

授课表 school_teaching
1. 指定字段插入数据

序号	课程号	教师号	周数	教室号
1	C1	T1	13	Y201
	C2	T1		Y202

输入

insert into school_teaching(id, course_no,teacher_no,week,class_num) values
-> ("1","c1","t1","13","y201"),
-> ("2","c2","t1","0","y202");

查看

1. 所有字段插入数据

序号	课程号	教师号	周数	教室号
	C3	T2	16	J101
4	C3	T3		J302

输入

mysql> insert into school_teaching values
-> ("3","c3","t2","16","y101"),
-> ("4","c3","t3","0","y302");

查看

1. 所有字段批量插入数据

序号	课程号	教师号	周数	教室号
	C4	T4		J102
6	C5	T6	8	Y402
	C5	T7	8	Y401

输入

insert into school_teaching values
-> ("5","c4","t4","0","j102"),
-> ("6","c5","t6","8","y402"),
-> ("7","c5","t7","8","y401");

查看

1. 指定字段批量插入数据

序号	课程号	教师号	周数	教室号
	C6	T5		Y303
	C7	T8		J201
	C8	T9		Y102

输入

insert into school_teaching(id, course_no,teacher_no,week,class_num) values
-> ("8","c6","t5","0","y303"),
-> ("9","c7","t8","0","y201"),
-> ("10","c8","t9","0","y102");
Query OK, 3 rows affected (0.01 sec)