MYSQL在进行登陆时，会去匹配mysql库中的user表，并赋予相应的权限 在MYSQL中，有两个函数，一个是 user(),一个是 current_user();
user()是用来显示当前登陆的用户名与它对应的host， currrent_user()是用来显示当前登陆用户对应在user表中的哪一个。
mysql> select user(); +----------------------+ | user() | +----------------------+ | test@192.168.203.132 | +----------------------+ 1 row in set (0.00 sec) mysql> select current_user(); +------------------+ | current_user() | +------------------+ | test@192.168.%.% | +------------------+ 1 row in set (0.00 sec)
一、有什么权限 所以假如我们想知道当前登陆的用户具有什么权限的话，第一步是找出当前登陆用户是用user表中的哪一个，用current_user()。
mysql> select current_user(); +----------------+ | current_user() | +----------------+ | root@localhost | +----------------+ 1 row in set (0.01 sec)
第二步用show grants命令
mysql> show grants for 'root'@'localhost'; +---------------------------------------------------------------------+ | 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)
二、如果针对用户网段有限制，匹配哪一个
mysql> grant select on *.* to test@192.168.203.132 identified by '000000'; Query OK, 0 rows affected (0.00 sec) mysql> grant select,update on *.* to 'test'@'192.168.203.%' identified by '000000'; Query OK, 0 rows affected (0.01 sec) mysql> grant select,update,insert on *.* to 'test'@'192.168.%.%' identified by '000000'; Query OK, 0 rows affected (0.01 sec) mysql> grant select,update,insert,delete on *.* to 'test'@'192.%.%.%' identified by '000000'; Query OK, 0 rows affected (0.00 sec)
可以用，进一步查看
mysql> use mysql; Database changed mysql> select user,host from user order by user,host;
select current_user();可以每次获取到匹配的网段的，而select user();的是具体的ip的。
mysql在登陆时会用最精确匹配user表中的帐户，host来作为当前的用户。
