1.检查并卸载mariadb
yum remove *mariadb*
遇到要求输入直接y/n 直接输入y回车
2.下载并安装mysql
mysql源地址：https://repo.mysql.com/
找到自己需要的版本，把版本名和 mysql源地址拼接起来，列如：我下载的是mysql80-community-release-el7.rpm,所以拼接起来就是filei下载地址 https://repo.mysql.com/mysql80-community-release-el7.rpm
wget https://repo.mysql.com/mysql80-community-release-el7.rpm
yum -y install mysql80-community-release-el7.rpm
3.安装并启动mysql服务器
yum -y install mysql-community-server
systemctl start mysqld.service
systemctl enable mysqld.service
systemctl daemon-reload