yum安装mysql5.5

删除原来的

 rpm -qa | grep -i mysql
 rpm -qa | grep maria
  rpm -e --nodeps mysql-community-libs-5.6.51-2.el7.x86_64
  sudo rm -rf /etc/my.cnf
  sudo find / -name mysql -type d -exec rm -rf {} \;
  sudo find / -name mysql -type f -exec rm -rf {} \;
  sudo yum makecache
  

然后按照这个文章安装
https://blog.youkuaiyun.com/weixin_42223120/article/details/113148081

然后找密码
https://blog.51cto.com/u_16213689/6980948