MySQL root 用户 UPDATE 命令被拒绝

Question

我尝试使用 root 用户更改 sql_mode 全局变量 perfomance_schema.global_variables 表。

我尝试使用SET GLOBAL sql_mode='???'；

但它不起作用。

当我展示我的根授权时，我认为我拥有正确的权利：

libertalia@labuse:~$ mysql -u root -p
Enter password: 
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 2
Server version: 5.7.23 MySQL Community Server (GPL)

Copyright (c) 2000, 2018, 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> show grants;
    +---------------------------------------------------------------------+
    | Grants for root@localhost                                           |
    +---------------------------------------------------------------------+
    | GRANT ALL PRIVILEGES ON *.* TO 'root'@'localhost' WITH GRANT OPTION |
    | GRANT PROXY ON ''@'' TO 'root'@'localhost' WITH GRANT OPTION        |
    +---------------------------------------------------------------------+
    2 rows in set (0,00 sec)

下一步，我尝试更改 sql_mode 全局变量：

mysql> use performance_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> describe global_variables;
+----------------+---------------+------+-----+---------+-------+
| Field          | Type          | Null | Key | Default | Extra |
+----------------+---------------+------+-----+---------+-------+
| VARIABLE_NAME  | varchar(64)   | NO   |     | NULL    |       |
| VARIABLE_VALUE | varchar(1024) | YES  |     | NULL    |       |
+----------------+---------------+------+-----+---------+-------+
2 rows in set (0,01 sec)

mysql> SELECT * FROM global_variables WHERE VARIABLE_NAME = 'sql_mode';
+---------------+-------------------------------------------------------------------------------------------------------------------------------------------+
| VARIABLE_NAME | VARIABLE_VALUE                                                                                                                            |
+---------------+-------------------------------------------------------------------------------------------------------------------------------------------+
| sql_mode      | ONLY_FULL_GROUP_BY,STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION |
+---------------+-------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0,01 sec)

mysql> UPDATE global_variables SET VARIABLE_VALUE = 'ONLY_FULL_GROUP_BY,ALLOW_INVALID_DATES,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION' WHERE VARIABLE_NAME = 'sql_mode';
ERROR 1142 (42000): UPDATE command denied to user 'root'@'localhost' for table 'global_variables'

我不明白为什么我的“root”超级用户不能更新这个表？ “root”是否拥有正确的权限？ MySQL 是否保护系统表？

要更改 sql_mode 变量，我是否需要 SUPER 权限但不需要 ALL PRIVILEGES ？这就是 SET GLOBAL sql_mode 也不起作用的原因吗？

Answer 1

information_schema 通常是只读视图。

INFORMATION_SCHEMA 是每个 MySQL 实例中的一个数据库，该位置存储有关 MySQL 服务器维护的所有其他数据库的信息。 INFORMATION_SCHEMA 数据库包含几个只读表。它们实际上是视图，而不是基表，因此没有与它们关联的文件，并且您不能在它们上设置触发器。此外，没有同名的数据库目录。

虽然您可以使用 USE 语句选择 INFORMATION_SCHEMA 作为默认数据库，但您只能读取表的内容，不能对其执行 INSERT、UPDATE 或 DELETE 操作。