MySQL列权限管理讲义

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列权限管理

            MySQL是由列级别权限存在的。这也体现了MySQL高级特性。实现了限制用户对表上特定列的访问权限。            一般都是实现对表级别不具备访问权限，但是对某些列有访问权限。当然也存在其他情形。

1# 列权限相关的字典表：

(root@localhost)[mysql]> desc columns_priv;+-------------+----------------------------------------------+------+-----+-------------------+-----------------------------+| Field       | Type                                         | Null | Key | Default           | Extra                       |+-------------+----------------------------------------------+------+-----+-------------------+-----------------------------+| Host        | char(60)                                     | NO   | PRI |                   |                             || Db          | char(64)                                     | NO   | PRI |                   |                             || User        | char(16)                                     | NO   | PRI |                   |                             || Table_name  | char(64)                                     | NO   | PRI |                   |                             || Column_name | char(64)                                     | NO   | PRI |                   |                             || Timestamp   | timestamp                                    | NO   |     | CURRENT_TIMESTAMP | on update CURRENT_TIMESTAMP || Column_priv | set('Select','Insert','Update','References') | NO   |     |                   |                             |+-------------+----------------------------------------------+------+-----+-------------------+-----------------------------+7 rows in set (0.00 sec)

            总共7列，很好理解。一条特定的列级别权限共需要定义5个维度，host+db+user+table+column。可授予的            权限种类分为4中，select, insert, update, refernces。其中前3项已经投入使用，references在5.6中还未正式            生效。

2# 授权方法
列权限的授权方法和其他维度的授权方法有些许的差异，因为并非按照想像中会用on db.table.column这样的形式，而是将列名附带在授权种类之后：
测试update，确认没有update权限在name列上，表上也没有。

(test1@localhost)[sample2]> update smp set name='bbb';ERROR 1142 (42000): UPDATE command denied to user 'test1'@'localhost' for table 'smp'(test1@localhost)[sample2]> 

            对name列授权update：

(root@localhost)[mysql]> grant update (name) on sample2.smp to test1;Query OK, 0 rows affected (0.00 sec)

            再次尝试update  name列，更新成功。

(test1@localhost)[sample2]> update smp set name='bbb';Query OK, 1 row affected (0.00 sec)Rows matched: 1  Changed: 1  Warnings: 0

            验证update  id列，可以预见的失败：

(test1@localhost)[sample2]> update smp set id=2;ERROR 1143 (42000): UPDATE command denied to user 'test1'@'localhost' for column 'id' in table 'smp'

3# 权限的查询：
4个方式，一个是show grants，另一个是跑sql查询字典表,DBA可以查询mysql.columns_priv, 普通用户可以查询information_schema.COLUMN_PRIVILEGES。两者有细微的差别，但主要列一样,第四种方式是查询mysql.tables_priv。

#1，直接show grants(root@localhost)[mysql]> show grants for test1;+------------------------------------------------------------------------------------------------------+| Grants for test1@%                                                                                   |+------------------------------------------------------------------------------------------------------+| GRANT USAGE ON *.* TO 'test1'@'%' IDENTIFIED BY PASSWORD '*CFA887C680E792C2DCF622D56FB809E3F8BE63CC' || GRANT SELECT ON `sample2`.* TO 'test1'@'%'                                                           || GRANT ALL PRIVILEGES ON `sample`.* TO 'test1'@'%' WITH GRANT OPTION                                  || GRANT SELECT ON `mysql`.`user` TO 'test1'@'%'                                                        || GRANT UPDATE (name) ON `sample2`.`smp` TO 'test1'@'%'                                                || GRANT ALL PRIVILEGES ON `sample`.`smp` TO 'test1'@'%'                                                |+------------------------------------------------------------------------------------------------------+6 rows in set (0.00 sec)#2，查询mysql.columns_priv;(root@localhost)[mysql]> select * from mysql.columns_priv;+------+---------+-------+------------+-------------+---------------------+-------------+| Host | Db      | User  | Table_name | Column_name | Timestamp           | Column_priv |+------+---------+-------+------------+-------------+---------------------+-------------+| %    | sample2 | test1 | smp        | name        | 0000-00-00 00:00:00 | Update      |+------+---------+-------+------------+-------------+---------------------+-------------+1 row in set (0.00 sec)#3，查询information_schema.COLUMN_PRIVILEGES(root@localhost)[mysql]> select * from information_schema.COLUMN_PRIVILEGES;+-------------+---------------+--------------+------------+-------------+----------------+--------------+| GRANTEE     | TABLE_CATALOG | TABLE_SCHEMA | TABLE_NAME | COLUMN_NAME | PRIVILEGE_TYPE | IS_GRANTABLE |+-------------+---------------+--------------+------------+-------------+----------------+--------------+| 'test1'@'%' | def           | sample2      | smp        | name        | UPDATE         | NO           |+-------------+---------------+--------------+------------+-------------+----------------+--------------+1 row in set (0.00 sec)#4，查询mysql.tables_priv(root@localhost)[mysql]> select * from mysql.tables_priv where db='sample2';+------+---------+-------+------------+----------------+---------------------+------------+-------------+| Host | Db      | User  | Table_name | Grantor        | Timestamp           | Table_priv | Column_priv |+------+---------+-------+------------+----------------+---------------------+------------+-------------+| %    | sample2 | test1 | smp        | root@localhost | 0000-00-00 00:00:00 |            | Update      |+------+---------+-------+------------+----------------+---------------------+------------+-------------+1 row in set (0.00 sec)

程序权限管理

            MySQL的程序（process/routine）            一个全局权限：CREATE ROUTINE，在user,db表中体现            三个对象级权限，主要分为procedure和function两个对象类型。对于程序而言他们的权限种类有            1，EXECUTE #执行权限            2，ALTER ROUTINE #修改权限            3，GRANT  #授予权限            相关的字典表：

(root@localhost)[mysql]> desc procs_priv;+--------------+----------------------------------------+------+-----+-------------------+-----------------------------+| Field        | Type                                   | Null | Key | Default           | Extra                       |+--------------+----------------------------------------+------+-----+-------------------+-----------------------------+| Host         | char(60)                               | NO   | PRI |                   |                             || Db           | char(64)                               | NO   | PRI |                   |                             || User         | char(16)                               | NO   | PRI |                   |                             || Routine_name | char(64)                               | NO   | PRI |                   |                             || Routine_type | enum('FUNCTION','PROCEDURE')           | NO   | PRI | NULL              |                             || Grantor      | char(77)                               | NO   | MUL |                   |                             || Proc_priv    | set('Execute','Alter Routine','Grant') | NO   |     |                   |                             || Timestamp    | timestamp                              | NO   |     | CURRENT_TIMESTAMP | on update CURRENT_TIMESTAMP |+--------------+----------------------------------------+------+-----+-------------------+-----------------------------+
8 rows in set (0.00 sec)

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