revoke错误 ERROR 1141 (42000):
mysql> grant all privileges on *.* to b@'%' identified by 'b' with grant option;
Query OK, 0 rows affected (0.00 sec)
mysql> revoke all on atest.* from b@'%';
ERROR 1141 (42000): There is no such grant defined for user 'b' on host '%'
mysql>
如何回收用户 b 的一个数据库权限?