SQL笔记--(6)--[授权]

授权

权限种类

privileges: select, insert, update, delete, all privileges

授权语句

grant 
    on 
    to 

其中可以是：public, user-id, role

grant select on student to Amit

grant select(ID) on student to Satoshi

权限回收

revoke 
    on 
    from 

revoke select on department from Amit
revoke select(budget) on department from Satoshi

权限授予图

大多数数据库中，级联是默认行为。

可以通过如下语句防止级联：

revoke select on department from Amit, Satoshi restrict;

以下语句显式指定级联回收：

revoke select on department from Amit, Satoshi cascade;

以下语句仅仅回收用户再授权的权限：

revoke grant option for select on department from Amit;

roles

create role Instructor;
grant Instructor to Mr.Wang; 将role授予用户
grant select on takes to Instrucor; 授予role以takes关系上的select权限
create role dean;   
grant Instructor to dean;    将role授予其他role

权限的转移

获得了某些形式权限的用户可能被允许将此授权传递给其他用户。默认方式下：被授予权限的用户/role无权再授予。

允许其再授予：grant select on department to Amit with grant option