1.删除CentOS默认安装的mariadb数据库
yum remove mariadb-libs.x86_64
2.下载mysql源文件 cd /tmp 目录下
wget https://repo.mysql.com/mysql57-community-release-el7-8.noarch.rpm
3.安装源
yum localinstall mysql57-community-release-el7-8.noarch.rpm
4.安装MySQL
yum install mysql-community-server
5.启动
sudo service mysqld start
6.查看默认密码
cat /var/log/mysqld.log | grep "password"
7.重置密码，查看文章(需先用默认密码登录mysql )
http://blog.sina.com.cn/s/blog_a0d71a9d0102wlz3.html
mysql -u root -p
注意：如果只想设置简单密码需要修改两个全局参数：
mysql> set global validate_password_policy=0;
mysql> set global validate_password_length=1;
mysql> SET PASSWORD = PASSWORD('123456'); //123456 是重置的新密码
8.设置root可以远程连接
update mysql.`user` set Host = '%' where User = 'root' and Host = 'localhost';
flush privileges; // 或者重启服务 sudo service mysqld restart
9.关闭防火墙
sudo service firewalld stop
