Ubuntu 19.04 安装 MySQL 5.7.27 Community（社区版）Server

1. 下载需要的包：
   下载顺序就是安装顺序。

   wget http://repo.mysql.com/apt/ubuntu/pool/mysql-5.7/m/mysql-community/mysql-community-client_5.7.27-1ubuntu19.04_amd64.deb
   
   wget http://repo.mysql.com/apt/ubuntu/pool/mysql-5.7/m/mysql-community/mysql-client_5.7.27-1ubuntu19.04_amd64.deb
   
   wget http://repo.mysql.com/apt/ubuntu/pool/mysql-5.7/m/mysql-community/mysql-community-server_5.7.27-1ubuntu19.04_amd64.deb

2. 安装 MySQL 依赖：

   sudo apt-get install libaio1 libmecab2

3. 安装 MySQL 并设置 root 密码：

   sudo dpkg -i mysql-community-client_5.7.27-1ubuntu19.04_amd64.deb
   
   sudo dpkg -i mysql-client_5.7.27-1ubuntu19.04_amd64.deb
   
   sudo dpkg -i mysql-community-server_5.7.27-1ubuntu19.04_amd64.deb

   安装最后一个包时，会弹窗，让你设置 root 密码：
   
    
4. 安装完成自动启动，包括设置开机自启。
    
5. 登录：
   Server version: 5.7.27 MySQL Community Server (GPL)

   xuxiaowei@virtual-machine:~$ mysql -u root -p
   Enter password: 
   Welcome to the MySQL monitor.  Commands end with ; or \g.
   Your MySQL connection id is 2
   Server version: 5.7.27 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> 
   

6. 安装完成自动启动，包括设置开机自启。
   1. 查看状态：

      systemctl status mysql.service

   2. 关闭：

      systemctl stop mysql.service

   3. 开启：

      systemctl start mysql.service

   4. 查看开机启动：

      systemctl list-unit-files |grep mysql
      

   5. 关闭开机启动：
      需要使用 root 进行操作。

      systemctl disable mysql.service

   6. 打开开机启动：
      需要使用 root 用户进行操作。

      systemctl enable mysql.service