今天登入mysql（Server version: 5.7.11） 還是很好的，今天登入後執行任何命令都報下面的錯誤

mysql> help contents
ERROR 1820 (HY000): You must reset your password using ALTER USER statement before executing this statement.
mysql> help contents
ERROR 1820 (HY000): You must reset your password using ALTER USER statement before executing this statement.
mysql> show databases;
ERROR 1820 (HY000): You must reset your password using ALTER USER statement before executing this statement.

解決辦法
1、 修改使用者密碼
mysql> alter user 'root'@'localhost' identified by 'youpassword';  

或者       

mysql> set password=password("youpassword");
2、重新整理許可權
mysql> flush privileges;

mysql> help contents
You asked for help about help category: "Contents"
For more information, type 'help <item>', where <item> is one of the following
categories:
   Account Management
   Administration
   Compound Statements
   Data Definition
   Data Manipulation
   Data Types
   Functions
   Functions and Modifiers for Use with GROUP BY
   Geographic Features
   Help Metadata
   Language Structure
   Plugins
   Procedures
   Storage Engines
   Table Maintenance
   Transactions
   User-Defined Functions
   Utility
mysql> show databases
-> ^C
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| sys |
+--------------------+
4 rows in set (0.01 sec)

mysql>
mysql>

問題解決，希望能幫助到大家。