mysql数据库在使用过程中user表中突然多了两个user为空的记录，如下：
mysql> select Host, user,password from user;
+-----------+--------+-------------------------------------------+
| Host | user | password |
+-----------+--------+-------------------------------------------+
| localhost | root | * xxxxxxxxxxxxxxxx |
| abcde | root | * xxxxxxxxxxxxxxxx |
| 127.0.0.1 | root | * xxxxxxxxxxxxxxxx |
| localhost | | |
| abcde | | |
| % | root | * xxxxxxxxxxxxxxxx |
| % | server | * xxxxxxxxxxxxxxxx |
+-----------+--------+-------------------------------------------+这两条user为空的记录是怎么产生的？
