1、问题重现
前几天因为有人删除了数据库中的记录，今天关闭了数据库的远程访问功能，今天接到开发报告，说出现 The user specified as a definer (‘air’@’%’) does not exist错误，他们定位是一张视图不能访问。利用实验重现了他们的情况

[root@ECP-UC-DB1 ~]# mysql -uxff -pxifenfei
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 8846
Server version: 5.5.14-log MySQL Community Server (GPL)
Copyright (c) 2000, 2010, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql> select user,host from mysql.user;
+------+---------------+
| user | host          |
+------+---------------+
| xff  | %             |
| root | 127.0.0.1     |
| repl | 192.168.11.10 |
| root | ::1           |
|      | ECP-UC-DB1    |
| root | ECP-UC-DB1    |
| root | localhost     |
+------+---------------+
7 rows in set (0.08 sec)
mysql> use xifenfei;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A
Database changed
mysql> create view v_users as select * from wp_users;
Query OK, 0 rows affected (0.14 sec)
mysql> select count(*) from xifenfei.v_users;
+----------+
| count(*) |
+----------+
|        2 |
+----------+
1 row in set (0.03 sec)
mysql> update mysql.user set host='localhost' where user='xff' and host='%';
Query OK, 1 row affected (0.05 sec)
Rows matched: 1  Changed: 1  Warnings: 0
mysql> FLUSH PRIVILEGES;
Query OK, 0 rows affected (0.12 sec)
mysql> exit
Bye
[root@ECP-UC-DB1 ~]# mysql -uxff -pxifenfei
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 8847
Server version: 5.5.14-log MySQL Community Server (GPL)
Copyright (c) 2000, 2010, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql> use xff;
ERROR 1049 (42000): Unknown database 'xff'
mysql> use xifenfei;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A
Database changed
mysql> select * from v_users ;
ERROR 1449 (HY000): The user specified as a definer ('xff'@'%') does not exist

2、解决方法

mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| test               |
| xifenfei           |
+--------------------+
5 rows in set (0.00 sec)
mysql> use information_schema;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A
Database changed
mysql> desc VIEWS;
+----------------------+--------------+------+-----+---------+-------+
| Field                | Type         | Null | Key | Default | Extra |
+----------------------+--------------+------+-----+---------+-------+
| TABLE_CATALOG        | varchar(512) | NO   |     |         |       |
| TABLE_SCHEMA         | varchar(64)  | NO   |     |         |       |
| TABLE_NAME           | varchar(64)  | NO   |     |         |       |
| VIEW_DEFINITION      | longtext     | NO   |     | NULL    |       |
| CHECK_OPTION         | varchar(8)   | NO   |     |         |       |
| IS_UPDATABLE         | varchar(3)   | NO   |     |         |       |
| DEFINER              | varchar(77)  | NO   |     |         |       |
| SECURITY_TYPE        | varchar(7)   | NO   |     |         |       |
| CHARACTER_SET_CLIENT | varchar(32)  | NO   |     |         |       |
| COLLATION_CONNECTION | varchar(32)  | NO   |     |         |       |
+----------------------+--------------+------+-----+---------+-------+
10 rows in set (0.02 sec)
mysql> select TABLE_SCHEMA,TABLE_NAME,DEFINER from views;
+--------------+------------+---------+
| TABLE_SCHEMA | TABLE_NAME | DEFINER |
+--------------+------------+---------+
| xifenfei     | v_users    | xff@%   |
+--------------+------------+---------+
1 row in set (0.16 sec)
mysql> create or replace view v_users as select * from wp_users;
ERROR 1044 (42000): Access denied for user 'xff'@'localhost' to database 'information_schema'
mysql> create or replace view xifenfei.v_users as select * from xifenfei.wp_users;
Query OK, 0 rows affected (0.02 sec)
mysql> select TABLE_SCHEMA,TABLE_NAME,DEFINER from views;
+--------------+------------+---------------+
| TABLE_SCHEMA | TABLE_NAME | DEFINER       |
+--------------+------------+---------------+
| xifenfei     | v_users    | xff@localhost |
+--------------+------------+---------------+
1 row in set (0.01 sec)
mysql> select count(*) from xifenfei.v_users;
+----------+
| count(*) |
+----------+
|        2 |
+----------+
1 row in set (0.03 sec)

3、原因分析
因为创建视图使用的是xff@%用户(目前已经不存在)，然后登录用户使用的是xff@localhost用户，导致mysql认为现在的用户无权限访问该视图，解决方法就是在当前用户下重建该视图