建立用户的时候报告这个错误：

ERROR 1396 (HY000): Operation CREATE USER failed for 'abc'@'localhost'

原因是mysql中已经有了这个用户，从mysql.user中直接删除delete，然后刷新权限FLUSH PRIVILEGES，再建用户就不会有这个问题了。

如果是drop user 的话，mysql内部会自动刷新一下，那么再建也不会有这问题了。

举例说明1——delete删除：

mysql> create user 'abc'@'localhost';

Query OK, 0 rows affected (0.00 sec)

mysql> select user,host from user;

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

| user | host |

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

| root | 127.0.0.1 |

| abc | localhost |

| root | localhost |

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

3 rows in set (0.00 sec)

mysql> delete from user where user='abc';

Query OK, 1 row affected (0.00 sec)

mysql> select user,host from user;

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

| user | host |

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

| root | 127.0.0.1 |

| root | localhost |

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

2 rows in set (0.00 sec)

再次创建同名用户，报错如下：

mysql> create user 'abc'@'localhost';

ERROR 1396 (HY000): Operation CREATE USER failed for 'abc'@'localhost'

这里要刷新权限，刷新之后就可以创建了；

mysql> flush privileges;

Query OK, 0 rows affected (0.00 sec)

mysql> create user 'abc'@'localhost';

Query OK, 0 rows affected (0.00 sec)

mysql> select user,host from user;

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

| user | host |

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

| root | 127.0.0.1 |

| abc | localhost |

| root | localhost |

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

3 rows in set (0.00 sec)

举例说明2——drop 删除，可以直接创建：

mysql> drop user 'abc'@'localhost';

Query OK, 0 rows affected (0.00 sec)

mysql> select user,host from user;

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

| user | host |

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

| root | 127.0.0.1 |

| root | localhost |

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

2 rows in set (0.00 sec)

mysql> create user 'abc'@'loaclhost';

Query OK, 0 rows affected (0.00 sec)