wget—从网址下载文件
    yum install wget

    1. 下载mysql的repo源

    $ wget http://repo.mysql.com/mysql-community-release-el7-5.noarch.rpm
    2. 安装mysql-community-release-el7-5.noarch.rpm包

    $ sudo rpm -ivh mysql-community-release-el7-5.noarch.rpm
    安装这个包后，会获得两个mysql的yum repo源：/etc/yum.repos.d/mysql-community.repo，/etc/yum.repos.d/mysql-community-source.repo。

    1. 安装mysql

    $ sudo yum install mysql-server

    安装service命令
    yum install initscripts -y

    重启服务
    service mysqld restart