我似乎无法重新创建一个已删除的简单用户，即使以root用户身份在MySQL中也是如此。

我的情况是：用户’jack’曾经存在，但是我从mysql.user中删除了它以重新创建它。我在那张桌子上看不到任何痕迹。如果我对其他随机用户名（例如“
jimmy”）执行此命令，则该命令会正常工作（就像最初对“ jack”所做的一样）。

我已经做了些什么来破坏用户“ jack”，以及如何撤销该破坏，以便重新创建“ jack”作为此安装的MySQL的有效用户？

请参见下面的示例。（当然，最初，在创建“ jack”和将其删除之间有很多时间。）

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)