MySQL数据库及其ODBC接口的介绍(2)

五.MySQL的权限管理
  
        MySQL的权限管理非常复杂,可以说这是它的得意之处,安全的管理有利于系统的稳抖?
        基本原则:       [user] from [host] to [db] (of localhost)
  
        系统数据库mysql中有四个分区:func,user,db,host.其中后三个有关权限管理.
        它们的结构如下:
  
Database: mysql  Table: user  Rows: 3
+---------------+----------+------+-----+---------+-------+
| Field         | Type     | Null | Key | Default | Extra |
+---------------+----------+------+-----+---------+-------+
| Host          | char(60) |      | PRI |         |       |
| User          | char(16) |      | PRI |         |       |
| password      | char(16) |      |     |         |       |
| ......_priv   | char(1)  |      |     | N       |       |
+---------------+----------+------+-----+---------+-------+
  
Database: mysql  Table: db  Rows: 3
+-------------+----------+------+-----+---------+-------+
| Field       | Type     | Null | Key | Default | Extra |
+-------------+----------+------+-----+---------+-------+
| Host        | char(60) |      | PRI |         |       |
| Db          | char(32) |      | PRI |         |       |
| User        | char(16) |      | PRI |         |       |
| ......_priv | char(1)  |      |     | N       |       |
+-------------+----------+------+-----+---------+-------+
  
Database: mysql  Table: host  Rows: 0
+-------------+----------+------+-----+---------+-------+
| Field       | Type     | Null | Key | Default | Extra |
+-------------+----------+------+-----+---------+-------+
| Host        | char(60) |      | PRI |         |       |
| Db          | char(32) |      | PRI |         |       |
| ......_priv | char(1)  |      |     | N       |       |
+-------------+----------+------+-----+---------+-------+
  
        1.未在db表中列出的任意数据库,user表中的权限都为有效.

        可只在user表中设置某些superuser的权限,而在db表中不涉及.
        2.host只用来维护有效的server,缺省为空表,即为局域网内
        的所有机器.
        3.可用mysql -u root mysql命令修改权限.
        4.权限匹配时遵循的原则是:
                a. 表顺序: host -> db -> user;
                b. host和db域可有通配符%和_,表示所有和单个字符;
                c. 同一表中,也是 host->db->user域的顺序,无通配符优
                于有通配符;
                d. user域为空(''),表示匹配所有其他的用户;
                e. host可为机器名,localhost,IP,或通配符(如192.10.10.%),
                        但不允许用数字和点号开头(如123.321.1.edu.cn);
                f. 各表中的权限最后相"或";
        5.修改完之后,执行mysqladmin -u root reload更新.