系统版本：
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 2
Server version: 5.7.28-log

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忘记密码，编辑my.cnf服务配置文件
 [mysqld]段段中加入 skip-grant-tables语句，去掉认证
update user set password=password("root")where user='root';
修改密码之后，无法立刻操作mysql，退出之后，重新连接mysql
执行语句报错：
You must reset your password using ALTER USER statement before executing this statement
解决方案
set password = password("root");
该问题是由于密码授权过期导致