配置源：
rpm -ivh https://repo.mysql.com//mysql57-community-release-el7-11.noarch.rpm
安装：
yum install mysql-server
启动：
systemctl start mysqld.service
获取初始密码：
grep "password" /var/log/mysqld.log
修改root密码：
alter user user() identified by '123456';
开机自启动：
systemctl enable mysqld
systemctl daemon-reload