mysql服务

1. 关系型数据库介绍
   1.1 数据结构模型

数据结构模型主要有：

层次模型
网状结构
关系模型

关系模型：
二维关系：row，column

数据库管理系统：DBMS
关系：Relational，RDBMS
1.2 RDBMS专业名词（relational database manager system）

常见的关系型数据库管理系统：

MySQL：MySQL，MariaDB，Percona-Server
PostgreSQL：简称为pgsql
Oracle
MSSQL

事务：多个操作被当作一个整体对待就称为一个事务
要看一个关系型数据库是否支持事务，需要看其是否支持并满足ACID测试
ACID：ACID是事务的一个基本标准

A：Automicity，原子性
C：Consistency，一致性
I：Isolation，隔离性
D：Durability，持久性

如果你对ACID感兴趣，可以查看这里了解详细说明，ACID将不作为我们讲解的重点。

**SQL：**Structure Query Language，结构化查询语言

**约束：**constraint，向数据表提供的数据要遵守的限制

主键约束：一个或多个字段的组合，填入的数据必须能在本表中唯一标识本行。且必须提供数据，不能为空（NOT NULL）。
    一个表只能存在一个
惟一键约束：一个或多个字段的组合，填入的数据必须能在本表中唯一标识本行。允许为空（NULL）
    一个表可以存在多个
外键约束：一个表中的某字段可填入数据取决于另一个表的主键已有的数据
检查性约束

**索引：**将表中的一个或多个字段中的数据复制一份另存，并且这些数据需要按特定次序排序存储

关系运算：

选择：挑选出符合条件的行（部分行）
投影：挑选出需要的字段
连接

数据抽象方式：

物理层：决定数据的存储格式，即RDBMS在磁盘上如何组织文件
逻辑层：描述DB存储什么数据，以及数据间存在什么样的关系
视图层：描述DB中的部分数据

1.3 关系型数据库的常见组件

关系型数据库的常见组件有：

数据库：database
表：table，由行（row）和列（column）组成
索引：index
视图：view
用户：user
权限：privilege
存储过程：procedure
存储函数：function
触发器：trigger
事件调度器：event scheduler

1.4 SQL语句

SQL语句有三种类型：

DDL：Data Defination Language，数据定义语言
DML：Data Manipulation Language，数据操纵语言
DCL：Data Control Language，数据控制语言

2. mysql安装与配置

2.1 mysql安装

mysql安装方式有三种：

源代码：编译安装
二进制格式的程序包：展开至特定路径，并经过简单配置后即可使用
程序包管理器管理的程序包：
    rpm：有两种
        OS Vendor：操作系统发行商提供的
        项目官方提供的
    deb

//配置mysql的yum源
[root@localhost ~]# cd /usr/src/
[root@localhost src]# ls
debug  kernels
[root@localhost src]# wget http://dev.mysql.com/get/mysql57-community-release-el7-10.noarch.rpm
下载过程略
[root@localhost src]# ls
debug  kernels  mysql57-community-release-el7-10.noarch.rpm
[root@localhost src]# yum -y install mysql57-community-release-el7-10.noarch.rpm
Loaded plugins: fastestmirror, product-id, search-disabled-repos, subscription-
              : manager
This system is not registered with an entitlement server. You can use subscription-manager to register.
Examining mysql57-community-release-el7-10.noarch.rpm: mysql57-community-release-el7-10.noarch 
....
Installed:
  mysql57-community-release.noarch 0:el7-10

Complete!
[root@localhost ~]# ls /etc/yum.repos.d/
mysql-community.repo  mysql-community-source.repo


//安装mysql5.7
[root@localhost ~]# yum -y install mysql-community-server mysql-community-client mysql-community-common mysql-community-devel
Loaded plugins: fastestmirror, product-id, search-disabled-repos, subscription-
              : manager
This system is not registered with an entitlement server. You can use subscription-manager to register.
Loading mirror speeds from cached hostfile
Resolving Dependencies
--> Running transaction check
---> Package mysql-community-client.x86_64 0:5.7.23-1.el7 will be installed
--> Processing Dependency: mysql-community-libs(x86-64) >= 5.7.9 for package: mysql-community-client-5.7.23-1.el7.x86_64 
....
Installed:
  mysql-community-client.x86_64 0:5.7.23-1.el7
  mysql-community-common.x86_64 0:5.7.23-1.el7
  mysql-community-devel.x86_64 0:5.7.23-1.el7
  mysql-community-libs.x86_64 0:5.7.23-1.el7
  mysql-community-libs-compat.x86_64 0:5.7.23-1.el7
  mysql-community-server.x86_64 0:5.7.23-1.el7

Replaced:
  mariadb-libs.x86_64 1:5.5.56-2.el7

Complete!

3. mysql的程序组成

客户端
    mysql：CLI交互式客户端程序
    mysql_secure_installation：安全初始化，强烈建议安装完以后执行此命令
    mysqldump：mysql备份工具
    mysqladmin
服务器端
    mysqld

3.1 mysql工具使用

//语法：mysql [OPTIONS] [database]
//常用的OPTIONS：
    -uUSERNAME      //指定用户名，默认为root
    -hHOST          //指定服务器主机，默认为localhost，推荐使用ip地址
    -pPASSWORD      //指定用户的密码
    -P#             //指定数据库监听的端口，这里的#需用实际的端口号代替，如-P3307
    -V              //查看当前使用的mysql版本
    -e          //不登录mysql执行sql语句后退出，常用于脚本
    

[root@localhost ~]# mysql -V
mysql  Ver 14.14 Distrib 5.7.23, for Linux (x86_64) using  EditLine wrapper

习题

1.搭建mysql服务

2.创建一个以你名字为名的数据库，并创建一张表student，该表包含三个字段（id，name，age），表结构如下：

mysql> desc student;
±------±-------------±-----±----±--------±------+
| Field | Type | Null | Key | Default | Extra |
±------±-------------±-----±----±--------±------+
| id | int(11) | NO | | NULL | |
| name | varchar(100) | NO | | NULL | |
| age | tinyint(4) | YES | | NULL | |
±------±-------------±-----±----±--------±------+
3 rows in set (0.00 sec)

3.查看下该新建的表有无内容（用select语句）
4.往新建的student表中插入数据（用insert语句），结果应如下所示：

±—±------------±-----+
| id | name | age |
±—±------------±-----+
| 1 | tom | 20 |
| 2 | jerry | 23 |
| 3 | wangqing | 25 |
| 4 | sean | 28 |
| 5 | zhangshan | 26 |
| 6 | zhangshan | 20 |
| 7 | lisi | NULL |
| 8 | chenshuo | 10 |
| 9 | wangwu | 3 |
| 10 | qiuyi | 15 |
| 11 | qiuxiaotian | 20 |
±—±------------±-----+

5.修改lisi的年龄为50
6.以age字段降序排序
7.查询student表中年龄最小的3位同学
8.查询student表中年龄最大的4位同学
9.查询student表中名字叫zhangshan的记录
10.查询student表中名字叫zhangshan且年龄大于20岁的记录
11.查询student表中年龄在23到30之间的记录
12.修改wangwu的年龄为100
13.删除student中名字叫zhangshan且年龄小于等于20的记录

解答

1.配置MySQL的yum 源
[root@localhost ~]# wget http://dev.mysql.com/get/mysql57-community-release-el7-10.noarch.
[root@localhost ~]# ls
anaconda-ks.cfg mysql57-community-release-el7-10.noarch.rpm
开启服务 查看端口
[root@localhost ~]# systemctl restart mysqld
[root@localhost ~]# systemctl enable mysqld
[root@localhost ~]# ss -antl
State Recv-Q Send-Q Local Address:Port Peer Address:Port
LISTEN 0 128 :22 :
LISTEN 0 100 127.0.0.1:25 :
LISTEN 0 128 :::22 :::
LISTEN 0 100 ::1:25 ::: *
LISTEN 0 80 :::3306
查看临时密码
[root@localhost ~]# grep “password” /var/log/mysqld.log
2019-02-17T11:47:40.912923Z 1 [Note] A temporary password is generated for root@localhost: MBw1HnunrC_)
[root@localhost ~]# mysql -uroot -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 6
Server version: 5.7.25

mysql> //看到有这样的标识符则表示成功登录了 //修改mysql登录密码
mysql> set global validate_password_policy=0;

Query OK, 0 rows affected (0.00 sec) mysql> set global validate_password_length=1;

Query OK, 0 rows affected (0.01 sec)
mysql> ALTER USER ‘root’@‘localhost’ IDENTIFIED BY ‘gsh’;
Query OK, 0 rows affected (0.00 sec)

mysql> quit
Bye
为避免mysql自动升级，卸载开始的yum源
[root@localhost ~]# rpm -qa|grep mysql
mysql57-community-release-el7-10.noarch
mysql-community-common-5.7.24-1.el7.x86_64 mysql-community-client-5.7.24-1.el7.x86_64
mysql-community-libs-compat-5.7.24-1.el7.x86_64 mysql-community-libs-5.7.24-1.el7.x86_64
mysql-community-server-5.7.24-1.el7.x86_64
mysql-community-devel-5.7.24-1.el7.x86_64
[root@localhost ~]# yum -y remove mysql57-community-release-el7-10.noarch

2.创建一个以你名字为名的数据库，并创建一张表student，该表包含三个字段（id，name，age），表结构如下：

[root@localhost ~]# mysql -uroot -p
Enter password: 
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 11
Server version: 5.7.25 MySQL Community Server (GPL)

Copyright (c) 2000, 2019, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> create database gsh;
Query OK, 1 row affected (0.00 sec)

mysql> use gsh;
Database changed
mysql> create table student(id int(10),name varchar(50),age int(10));
Query OK, 0 rows affected (0.03 sec)

mysql> desc students;
ERROR 1146 (42S02): Table 'gsh.students' doesn't exist
mysql> desc student;
+-------+-------------+------+-----+---------+-------+
| Field | Type        | Null | Key | Default | Extra |
+-------+-------------+------+-----+---------+-------+
| id    | int(10)     | YES  |     | NULL    |       |
| name  | varchar(50) | YES  |     | NULL    |       |
| age   | int(10)     | YES  |     | NULL    |       |
+-------+-------------+------+-----+---------+-------+
3 rows in set (0.01 sec)

3.查看下该新建的表有无内容（用select语句）

mysql> select * from student;
Empty set (0.00 sec)

4.往新建的student表中插入数据（用insert语句），结果应如下所示：

mysql> insert student(id,name,age) value (1,'tom',20),(2,'jerry',23),(3,'wangqing',25),(4,'sean',28),(5,'zhangshan',26),(6,'zhangshan',20),(7,'lisi',null),(8,'chengshuo',10),(9,'wangwu',3),(10,'qiuyi',15),(11,'qiuxiaotian',20);
Query OK, 11 rows affected (0.06 sec)
Records: 11  Duplicates: 0  Warnings: 0

mysql> select * from student;
+------+-------------+------+
| id   | name        | age  |
+------+-------------+------+
|    1 | tom         |   20 |
|    2 | jerry       |   23 |
|    3 | wangqing    |   25 |
|    4 | sean        |   28 |
|    5 | zhangshan   |   26 |
|    6 | zhangshan   |   20 |
|    7 | lisi        | NULL |
|    8 | chengshuo   |   10 |
|    9 | wangwu      |    3 |
|   10 | qiuyi       |   15 |
|   11 | qiuxiaotian |   20 |
+------+-------------+------+
11 rows in set (0.00 sec)

5.修改lisi的年龄为50

mysql> update student set age = 50 where name = 'lisi';
Query OK, 1 row affected (0.01 sec)
Rows matched: 1  Changed: 1  Warnings: 0

mysql> select * from student where name = 'lisi';
+------+------+------+
| id   | name | age  |
+------+------+------+
|    7 | lisi |   50 |
+------+------+------+
1 row in set (0.00 sec)

6.以age字段降序排序

mysql> select * from student order by age desc;
+------+-------------+------+
| id   | name        | age  |
+------+-------------+------+
|    7 | lisi        |   50 |
|    4 | sean        |   28 |
|    5 | zhangshan   |   26 |
|    3 | wangqing    |   25 |
|    2 | jerry       |   23 |
|    1 | tom         |   20 |
|    6 | zhangshan   |   20 |
|   11 | qiuxiaotian |   20 |
|   10 | qiuyi       |   15 |
|    8 | chengshuo   |   10 |
|    9 | wangwu      |    3 |
+------+-------------+------+
11 rows in set (0.00 sec)

7.查询student表中年龄最小的3位同学

mysql> select * from student order by age limit 3;
+------+-----------+------+
| id   | name      | age  |
+------+-----------+------+
|    9 | wangwu    |    3 |
|    8 | chengshuo |   10 |
|   10 | qiuyi     |   15 |
+------+-----------+------+
3 rows in set (0.00 sec)

8.查询student表中年龄最大的4位同学

mysql> select * from student order by age desc limit 4;
+------+-----------+------+
| id   | name      | age  |
+------+-----------+------+
|    7 | lisi      |   50 |
|    4 | sean      |   28 |
|    5 | zhangshan |   26 |
|    3 | wangqing  |   25 |
+------+-----------+------+
4 rows in set (0.00 sec)

9.查询student表中名字叫zhangshan的记录

mysql> select * from student where name = 'zhangshan';
+------+-----------+------+
| id   | name      | age  |
+------+-----------+------+
|    5 | zhangshan |   26 |
|    6 | zhangshan |   20 |
+------+-----------+------+
2 rows in set (0.00 sec)

10.查询student表中名字叫zhangshan且年龄大于20岁的记录

mysql> select * from student where age between 23 and 30;
+------+-----------+------+
| id   | name      | age  |
+------+-----------+------+
|    2 | jerry     |   23 |
|    3 | wangqing  |   25 |
|    4 | sean      |   28 |
|    5 | zhangshan |   26 |
+------+-----------+------+
4 rows in set (0.00 sec)

11.查询student表中名字叫zhangshan且年龄大于20岁的记录

mysql> select * from student where name = 'zhangshan' and age >=20;
+------+-----------+------+
| id   | name      | age  |
+------+-----------+------+
|    5 | zhangshan |   26 |
|    6 | zhangshan |   20 |
+------+-----------+------+
2 rows in set (0.00 sec)

12.修改wangwu的年龄为100

mysql> update student set age = 100 where name = 'wangwu';
Query OK, 1 row affected (0.00 sec)
Rows matched: 1  Changed: 1  Warnings: 0

mysql> select * from student where name = 'wangwu';
+------+--------+------+
| id   | name   | age  |
+------+--------+------+
|    9 | wangwu |  100 |
+------+--------+------+
1 row in set (0.00 sec)

13.删除student中名字叫zhangshan且年龄小于等于20的记录

mysql> delete from student where name = 'zhangshan' and age<=20;
Query OK, 1 row affected (0.00 sec)

mysql> select * from student;
+------+-------------+------+
| id   | name        | age  |
+------+-------------+------+
|    1 | tom         |   20 |
|    2 | jerry       |   23 |
|    3 | wangqing    |   25 |
|    4 | sean        |   28 |
|    5 | zhangshan   |   26 |
|    7 | lisi        |   50 |
|    8 | chengshuo   |   10 |
|    9 | wangwu      |  100 |
|   10 | qiuyi       |   15 |
|   11 | qiuxiaotian |   20 |
+------+-------------+------+
10 rows in set (0.00 sec)