MySQL权限篇之ALTER

根据mysql文档定义：

ALTER权限是：To alter the table。就是仅仅有更改表结构的权限。

mysql> grant alter on test.t1 to 'ut01'@'%';

Query OK, 0 rows affected (0.06 sec)

mysql> show grants for 'ut01'@'%';

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

| Grants for ut01@%                        |

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

| GRANT USAGE ON *.* TO 'ut01'@'%'         |

| GRANT ALTER ON `test`.`t1` TO 'ut01'@'%' |

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

2 rows in set (0.00 sec)

mysql> 

此时，'ut01'@'%'用户只有usage和在test.t1表的alter权限。

根据定义，该用户对于test.t1表只能alter表结构操作。

而不能进行select和dml操作，也不能执行alter table rename 操作。

下面验证：

mysql> select user();

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

| user()         |

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

| ut01@localhost |

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

1 row in set (0.00 sec)

mysql> use mysql

ERROR 1044 (42000): Access denied for user 'ut01'@'%' to database 'mysql'  #看不到其他库

mysql> use test

Database changed

mysql> show tables;

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

| Tables_in_test |

+----------------+ 

| t1             |   #看不到其他表

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

1 row in set (0.00 sec)

mysql> select * from t1;

ERROR 1142 (42000): SELECT command denied to user 'ut01'@'localhost' for table 't1'  #不能查询，很奇葩

mysql> desc t1;

Empty set (0.00 sec)

mysql> insert into t1(a,b,h) values(4,5,'pp');

ERROR 1142 (42000): INSERT command denied to user 'ut01'@'localhost' for table 't1'  #也不能插入

mysql> ALTER TABLE `test`.`t1` ADD COLUMN `g` BIT NULL AFTER `h`;

Query OK, 0 rows affected (0.81 sec)

Records: 0  Duplicates: 0  Warnings: 0

 #但是可以修改表结构，很奇葩

mysql> ALTER TABLE `test`.`t1` RENAME TO test.t2;

ERROR 1142 (42000): DROP command denied to user 'ut01'@'localhost' for table 't1' #重命名表失败

mysql> RENAME TABLE `test`.`t1` TO test.t2;

ERROR 1142 (42000): DROP command denied to user 'ut01'@'localhost' for table 't1' #这种方式重命名表也失败

mysql>

mysql> ALTER TABLE `test`.`t1` ADD INDEX (`category`);

Query OK, 0 rows affected (0.84 sec)

Records: 0  Duplicates: 0  Warnings: 0

mysql> ALTER TABLE `test`.`t1`

    ->   DROP INDEX `category`;

Query OK, 0 rows affected (0.32 sec)

Records: 0  Duplicates: 0  Warnings: 0

可以使用alter方式add和drop index，但是直接create index是不行的，当然drop index也不行。

mysql> CREATE INDEX idx_t1_category ON `test`.`t1`(`category`);

ERROR 1142 (42000): INDEX command denied to user 'ut01'@'localhost' for table 't1'

mysql>