mysql授权远程用户连接（权限最小化原则）

1、进入MySQL，创建一个新用户root,密码为root：

格式：grant 权限 on 数据库名.表名 to 用户@登录主机 identified by “用户密码”; 
grant select,update,insert,delete on . to root@192.168.1.12 identified by “root”;

原先数据表结构

mysql> use mysql;
Database changed
mysql> select host,user,password from user;
+-----------+------+-------------------------------------------+
| host      | user | password                                  |
+-----------+------+-------------------------------------------+
| localhost | root | *81F5E21E35407D884A6CD4A731AEBFB6AF209E1B |
+-----------+------+-------------------------------------------+

执行上述语句后结果

mysql> use mysql;
Database changed
mysql> select host,user,password from user;
+--------------+------+-------------------------------------------+
| host         | user | password                                  |
+--------------+------+-------------------------------------------+
| localhost    | root | *81F5E21E35407D884A6CD4A731AEBFB6AF209E1B |
| 192.168.1.12 | root | *81F5E21E35407D884A6CD4A731AEBFB6AF209E1B |
+--------------+------+-------------------------------------------+
2 rows in set (0.00 sec)

可以看到在user表中已有刚才创建的root用户。host字段表示登录的主机，其值可以用IP，也可用主机名， 
有时想用本地IP登录，那么可以将以上的Host值改为自己的Ip即可。

2、实现远程连接(授权法)

将host字段的值改为%就表示在任何客户端机器上能以root用户登录到mysql服务器，建议在开发时设为%。 
update user set host = ’%’ where user = ’root’;

将权限改为ALL PRIVILEGES

mysql> use mysql;
Database changed
mysql> grant all privileges  on *.* to root@'%' identified by "root";
Query OK, 0 rows affected (0.00 sec) 

mysql> select host,user,password from user;
+--------------+------+-------------------------------------------+
| host         | user | password                                  |
+--------------+------+-------------------------------------------+
| localhost    | root | *81F5E21E35407D884A6CD4A731AEBFB6AF209E1B |
| 192.168.1.12 | root | *81F5E21E35407D884A6CD4A731AEBFB6AF209E1B |
| %            | root | *81F5E21E35407D884A6CD4A731AEBFB6AF209E1B |
+--------------+------+-------------------------------------------+
3 rows in set (0.00 sec)

这样机器就可以以用户名root密码root远程访问该机器上的MySql.

3、实现远程连接（改表法）

use mysql;

update user set host = ‘%’ where user = ‘root’;

这样在远端就可以通过root用户访问Mysql.

 mysql假如授权 grant all privileges on *.* to 'huowuzhao'@'192.168.%' identified by 'password'；

再授权grant all privileges on *.* to 'huowuzhao'@'192.168.222.%' identified by 'password'；之后，之前授权的用户将失效，是因为mysql有权限最小化原则。