drop user mysql_MySQL似乎是DROP USER;但是用户仍然存在于mysql.users表中

我刚刚在Mac OS X 10.6.6上安装了

MySQL社区服务器(5.5.8).

我一直在遵循安全安装​​的规则(为root分配密码,删除匿名帐户等),但是,有一个用户帐户,我不能DROP：

mysql> select host, user from mysql.user;

+--------------------------------+------+

| host | user |

+--------------------------------+------+

| 127.0.0.1 | root |

| ::1 | root |

| My-Computer-Hostname.local | |

| My-Computer-Hostname.local | root |

| localhost | root |

| localhost | web |

+--------------------------------+------+

6 rows in set (0.00 sec)

mysql> drop user ''@'My-Computer-Hostname.local';

Query OK, 0 rows affected (0.00 sec)

mysql> flush privileges;

Query OK, 0 rows affected (0.00 sec)

mysql> select host, user from mysql.user;

+--------------------------------+------+

| host | user |

+--------------------------------+------+

| 127.0.0.1 | root |

| ::1 | root |

| My-Computer-Hostname.local | |

| My-Computer-Hostname.local | root |

| localhost | root |

| localhost | web |

+--------------------------------+------+

6 rows in set (0.00 sec)

mysql>

如您所见,MySQL在执行DROP USER命令时报告没有错误,但实际上并未删除用户！

我也尝试从phpMyAdmin(3.3.9)中删除用户并产生相同的结果(即报告成功,没有错误消息,用户未删除).

我研究了这个,有些人建议GRANT可能会阻止DROP USER命令,但是,用户没有GRANT权限：

mysql> SHOW GRANTS FOR ''@'My-Computer-Hostname.local';

+-----------------------------------------------------------+

| Grants for @my-computer-hostname.local |

+-----------------------------------------------------------+

| GRANT USAGE ON *.* TO ''@'my-computer-hostname.local' |

+-----------------------------------------------------------+

1 row in set (0.00 sec)

mysql> REVOKE GRANT OPTION ON *.* FROM ''@'My-Computer-Hostname.local';

ERROR 1141 (42000): There is no such grant defined for user '' on host 'my-computer-hostname.local'

之后我尝试再次删除用户,但它也没有删除/删除用户.

我已经检查了我的MySQl错误日志,那里没有什么异常.

MySQL手册表明可以删除所有匿名帐户,为什么我不能删除这个？