問題重現
前幾天因為有人刪除了資料庫中的記錄，今天關閉了資料庫的遠端存取功能，今天接到開發報告，說出現 The user specified as a definer (‘air’@'%’) does not exist錯誤，他們定位是一張視圖不能訪問。利用實驗重現了他們的情況
原因分析
因為建立視圖使用的是xff@%使用者(目前已經不存在)，然後登入使用者使用的是xff@localhost使用者，導致mysql認為現在的使用者無許可權訪問該視圖，解決方案就是在目前使用者下重建該視圖
我使用的代碼
| 代碼如下 |
複製代碼 |
[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、解決方案
| 代碼如下 |
複製代碼 |
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) |
1.注意事項
建立視圖存在如下注意事項：
（1） 運行建立視圖的語句需要使用者具有建立視圖（CRATE VIEW）的許可權，若加了[OR REPLACE]時，還需要使用者具有刪除視圖（DROP VIEW）的許可權；
（2） SELECT語句不能包含FROM子句中的子查詢；
（3） SELECT語句不能引用系統或使用者變數；
（4） SELECT語句不能引用預先處理語句參數；
（5） 在儲存子程式內，定義不能引用子程式參數或局部變數；
（6） 在定義中引用的表或視圖必須存在。但是，建立了視圖後，能夠捨棄定義引用的表或視圖。要想檢查視圖定義是否存在這類問題，可使用CHECK TABLE語句；
（7） 在定義中不能引用TEMPORARY表，不能建立TEMPORARY視圖；
（8） 在視圖定義中命名的表必須已存在；
（9） 不能將觸發程式與視圖關聯在一起；
（10） 在視圖定義中允許使用ORDER BY，但是，如果從特定視圖進行了選擇，而該視圖使用了具有自己ORDER BY的語句，它將被忽略。
補充一下mysql視圖基本知識
建立視圖——CREATE VIEW
1.文法
| 代碼如下 |
複製代碼 |
| CREATE [OR REPLACE] [ALGORITHM = {UNDEFINED | MERGE | TEMPTABLE}] VIEW [db_name.]view_name [(column_list)] AS select_statement [WITH [CASCADED | LOCAL] CHECK OPTION] |
通過該語句可以建立視圖，若給定了[OR REPLACE]，則表示當已具有同名的視圖時，將覆蓋原視圖。select_statement是一個查詢語句，這個查詢語句可從表或其它的視圖中查詢。視圖屬於資料庫，因此需要指定資料庫的名稱，若未指定時，表示在當前的資料庫建立新視圖。
表和資料庫共用資料庫中相同的名稱空間，因此，資料庫不能包含相同名稱的表和視圖，並且，視圖的列名也不能重複。
1.使用舉例
Eg. 本例建立一個產品表（product）和一個購買記錄表（purchase），再通過視圖purchase_detail查詢出購買的詳細資料。
| 代碼如下 |
複製代碼 |
CREATE TABLE product
(
product_id INT NOT NULL,
name VARCHAR(50) NOT NULL,
price DOUBLE NOT NULL
);
INSERT INTO product VALUES(1, 'apple ', 5.5);
CREATE TABLE purchase
(
id INT NOT NULL,
product_id INT NOT NULL,
qty INT NOT NULL DEFAULT 0,
gen_time DATETIME NOT NULL
);
INSERT INTO purchase VALUES(1, 1, 10, NOW());
CREATE VIEW purchase_detail AS SELECT product.name as name, product .price as price, purchase.qty as qty, product .price * purchase.qty as total_value from product, purchase where product.product_id = purchase.product_id; |
建立成功後，輸入：SELECT * FROM purchase_detail;
運行效果如下：
| 代碼如下 |
複製代碼 |
+-------+-------+-----+-------------+
| name | price | qty | total_value |
+-------+-------+-----+-------------+
| apple | 5.5 | 10 | 55 |
+-------+-------+-----+-------------+
1 row in set (0.01 sec) |
