做了一些privilege相關的操作，root用戶突然找不到系統的數據庫了，失去了root用戶的權限，找了好久才解決:

1. 關閉數據庫

   sudo /etc/init.d/mysql stop

2. 啟動安全模式數據庫

   mysqld_safe --skip-grant-tables &

3. 登錄數據庫，此時已是root用戶,查看root用戶

   mysql

   > use mysql;

   > select user,host from user;

4. 修改root用戶權限

update user set 
  `Select_priv` = ‘Y‘,
  `Insert_priv` = ‘Y‘,
  `Update_priv` = ‘Y‘,
  `Delete_priv` = ‘Y‘,
  `Create_priv` = ‘Y‘,
  `Drop_priv` = ‘Y‘,
  `Reload_priv` = ‘Y‘,
  `Shutdown_priv` = ‘Y‘,
  `Process_priv` = ‘Y‘,
  `File_priv` = ‘Y‘,
  `Grant_priv` = ‘Y‘,
  `References_priv` = ‘Y‘,
  `Index_priv` = ‘Y‘,
  `Alter_priv` = ‘Y‘,
  `Show_db_priv` = ‘Y‘,
  `Super_priv` = ‘Y‘,
  `Create_tmp_table_priv` = ‘Y‘,
  `Lock_tables_priv` = ‘Y‘,
  `Execute_priv` = ‘Y‘,
  `Repl_slave_priv` = ‘Y‘,
  `Repl_client_priv` = ‘Y‘,
  `Create_view_priv` = ‘Y‘,
  `Show_view_priv` = ‘Y‘,
  `Create_routine_priv` = ‘Y‘,
  `Alter_routine_priv` = ‘Y‘,
  `Create_user_priv` = ‘Y‘,
  `Event_priv` = ‘Y‘,
  `Trigger_priv` = ‘Y‘,
  `Create_tablespace_priv` = ‘Y‘
where user=‘root‘ and host=‘localhost‘;

最後重啟數據庫 /etc/init.d/mysql restart

如果碰到忘記root密碼也可以采用上面的方式登錄root賬號，

update user set authentication_string=password(‘new password‘) where user=‘root‘;

本文出自 “沈澱” 博客，請務必保留此出處http://jupiterbee.blog.51cto.com/3364619/1981109

Ubuntu mysql5.7 root用戶看不到數據庫