我似乎无法重新创建一个我已经删除的简单用户，即使是MySQL的根用户。

我的案例:用户'jack'之前存在，但我从mysql中删除了它。用户才能重新创建它。我在那张桌子上没看到这东西的痕迹。如果我对其他一些随机用户名执行这个命令，比如'jimmy'，它就能正常工作(就像它最初对'jack'所做的那样)。

我做了什么破坏用户'jack'，我如何撤销这个破坏，以重新创建'jack'作为MySQL安装的有效用户?

参见下面的示例。(当然，最初，jack这个词从被创造到被移除之间有很长一段时间。)

mysql> CREATE USER 'jack'@'localhost' IDENTIFIED BY 'test123';
Query OK, 0 rows affected (0.00 sec)

mysql> select user,host from user;
+------------------+-----------------+
| user             | host            |
+------------------+-----------------+
| root             | 127.0.0.1       |
| debian-sys-maint | localhost       |
| jack             | localhost       |
| root             | localhost       |
| root             | russ-elite-book |
+------------------+-----------------+
5 rows in set (0.00 sec)

mysql> delete from user where user = 'jack';
Query OK, 1 row affected (0.00 sec)

mysql> select user,host from user;
+------------------+-----------------+
| user             | host            |
+------------------+-----------------+
| root             | 127.0.0.1       |
| debian-sys-maint | localhost       |
| root             | localhost       |
| root             | russ-elite-book |
+------------------+-----------------+
4 rows in set (0.00 sec)

mysql> CREATE USER 'jack'@'localhost' IDENTIFIED BY 'test123';
ERROR 1396 (HY000): Operation CREATE USER failed for 'jack'@'localhost'
mysql> CREATE USER 'jimmy'@'localhost' IDENTIFIED BY 'test123';
Query OK, 0 rows affected (0.00 sec)

mysql> select user,host from user;
+------------------+-----------------+
| user             | host            |
+------------------+-----------------+
| root             | 127.0.0.1       |
| debian-sys-maint | localhost       |
| jimmy            | localhost       |
| root             | localhost       |
| root             | russ-elite-book |
+------------------+-----------------+
5 rows in set (0.00 sec)