mysql 版本5.17.21， 新建用户aa，授权查询权限。aa可以登录mysql，但不能做任何操作，提示如下错误。（test用户有管理员权限，都是正常的。）查询数据库show databases ：mysql> show databases;
ERROR 2006 (HY000): MySQL server has gone away
No connection. Trying to reconnect...
Connection id:    12
Current database: *** NONE ***

ERROR 1184 (08S01): Aborted connection 12 to db: 'unconnected' user: 'aa' host: 'localhost' (init_connect command failed)

系统查询的用户表信息：
select host,user,authentication_string from mysql.user;
+-----------+------------------+-------------------------------------------+
| host      | user             | authentication_string                     |
+-----------+------------------+-------------------------------------------+
| localhost | root             | *2BB8BBF7ECAFF5898BAFFB2AC93FF039F8B1445F |
| localhost | mysql.session    | *THISISNOTAVALIDPASSWORDTHATCANBEUSEDHERE |
| localhost | mysql.sys        | *THISISNOTAVALIDPASSWORDTHATCANBEUSEDHERE |
| localhost | debian-sys-maint | *2BB8BBF7ECAFF5898BAFFB2AC93FF039F8B1445F |
| %         | test             | *94BDCEBE19083CE2A1F959FD02F964C7AF4CFC29 |
| localhost | aa          | *3F6489C2293B20876945D05FC2638EBBFAECF275 |
+-----------+------------------+-------------------------------------------+
6 rows in set (0.00 sec)

授权查询
mysql> show grants for aa@'localhost';

+---------------------------------------------------+
| Grants for aahttps://bbs.deepin.org/user/72751                       |
+---------------------------------------------------+
| GRANT USAGE ON *.* TO 'aa'@'localhost'        |
| GRANT SELECT ON `world`.* TO 'aa'@'localhost' |
+---------------------------------------------------+
2 rows in set (0.00 sec)