系統版本：
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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忘記密碼，編輯my.cnf服務配置文件
[mysqld]段段中加入 skip-grant-tables語句，去掉認證
update user set password=password("root")where user='root';
修改密碼之後，無法立刻操作mysql，退出之後，重新連接mysql
執行語句報錯：
You must reset your password using ALTER USER statement before executing this statement
解決方案
set password = password("root");
該問題是由於密碼授權過期導致