CentOS 8 卸载Mysql8 安装mysql5.6
参考：https://www.cnblogs.com/alan-lin/p/9950389.htmlhttps://blog.csdn.net/weixin_36354744/article/details/113599916https://www.cnblogs.com/liuxgcn/p/11115252.htmlMysql的repo资源地址http://repo.mysql.com/下载mysql-community-release-el7.rpmwget http://repo.mysq
