1、下载命令
    wget https://dev.mysql.com/get/mysql57-community-release-el7-9.noarch.rpm
    2、yun源安装命令
    rpm -ivh mysql57-community-release-el7-9.noarch.rpm
    3、使用yum命令安装mysql
    yum -y install mysql-server
    4、启动mysql
    systemctl start mysqld
    5、检查是否安装启动成功
    systemctl status mysqld
    6、查看默认密码
    grep ‘temporary password’ /var/log/mysqld.log
    7、登录修改密码
    mysql -u root -p
    8、修改密码
    因为5.7及以上版本的数据库对密码做了强度要求，默认密码的要求必须是大小写字母数字特殊字母的组合且至少要8位长度
    ALTER USER ‘root’@’localhost’ IDENTIFIED BY ‘新的密码’;
    9、允许远程登录
    GRANT ALL PRIVILEGES ON . TO ‘root’@’%’ IDENTIFIED BY ‘密码’ WITH GRANT OPTION;
    10、如仍然无法访问则需关闭防火墙或者开放3306端口访问权限
    附：CentOS 7 关闭防火墙命令
    systemctl stop firewalld.service
    systemctl disable firewalld.service
    11.遇到密钥问题，
    rpm —importhttps://repo.mysql.com/RPM-GPG-KEY-mysql-2022
    再重新执行安装命令