oracle的role算是对sys privilege 和object privilege的打包。
今天深入的测试了下，还算有不少的东西。
role不是schema对象
像table等在一个schema里面不能有同名的schema object,但是可以有同名的table和role，如下。
SQL> conn test1/test1
Connected.
SQL> create role testrole;
Role created.
SQL> create table testrole as select *from all_objects;
Table created.
SQL> grant select on testrole to testrole;
Grant succeeded.
role和schema不同，有全局的意思。
--切换一个用户，把权限放进testrole里面。
SQL> conn test2/test2
Connected.
SQL> create table a as select *from obj;
Table created.
SQL> grant select on a to testrole;
Grant succeeded.
--但是话说回来，role testrole是test1用户创建的，用test2赋给其他用户的话是不允许。
SQL> grant testrole to test3;
grant testrole to test3
*
ERROR at line 1:
ORA-01919: role 'TESTROLE' does not exist
--用owner用户来赋予role testrole就没问题。
SQL> conn test1/test1
Connected.
SQL> grant testrole to test3;
Grant succeeded.
role是基于session级的
可以打开两个窗口，使用用户test1,test3来进行测试。
session1:
SQL> conn test1/test1
Connected.
SQL> create role testrole;
Role created.
session2:
SQL> conn test3/test3
Connected.
session1:
SQL> grant select on t1 to testrole;
Grant succeeded.
SQL> grant select on testrole to test3;
Grant succeeded.
session2:
SQL> desc test1.t1
ERROR:
ORA-04043: object test1.t1 does not exist
session2 再次登录：
SQL> conn test3/test3
Connected.
SQL> desc test1.t1
Name Null? Type
----------------------------------------- -------- ----------------------------
OBJECT_NAME VARCHAR2(128)
SUBOBJECT_NAME VARCHAR2(30)
OBJECT_ID NUMBER
DATA_OBJECT_ID NUMBER
OBJECT_TYPE VARCHAR2(19)
CREATED DATE
LAST_DDL_TIME DATE
TIMESTAMP VARCHAR2(19)
STATUS VARCHAR2(7)
TEMPORARY VARCHAR2(1)
GENERATED VARCHAR2(1)
SECONDARY VARCHAR2(1)
还有一点需要说明一下，如果直接赋予object privilege，在当前session就会生效，这也是和role的一个不同之处。
当前session激活role
可以使用set role或者dbms_session.set_role来激活。
role的限制
--> 在pl/sql中的限制
在动态sql中，如果调用某些表的时候，通过role，会有table or view not found这类的exception， 这时候需要通过直接赋予object privilege来修正。
-->创建视图时的问题
创建视图时，很可能会有insuffisicant privilege的错误。可以参见http://space.itpub.net/23718752/viewspace-762805/
role的加密
如果10个人用同一个db 账号，但是每个人又需要有不同的权限，可以对role加密。
这样每个人在使用的时候都能够相应的通过密码来激活属于自己的role。
SQL> create role user1_role identified by test1;
Role created.
SQL> create role user2_role identified by test2;
Role created.
SQL> create role user3_role identified by test3;
Role created.
SQL> create table t1 as select *from obj;
Table created.
SQL> create table t2 as select *from tab;
Table created.
SQL> create table t3 as select *from syn;
Table created.
SQL> grant select on t1 to user1_role;
Grant succeeded.
SQL> grant select on t2 to user2_role;
Grant succeeded.
SQL> grant select on t3 to user3_role;
Grant succeeded.
SQL> grant user1_role,user2_role,user3_role to test3;
Grant succeeded.
---初始化test3
SQL> conn / as sysdba
Connected.
--一下这句很关键，只指定用户test3有connect的角色
SQL> alter user test3 default role connect;
User altered.
--使用test3来连入，
SQL> conn test3/test3
Connected.
SQL> select *from session_roles;
ROLE
------------------------------
CONNECT
--先查看是否可以访问test1.t1
SQL> desc test1.t1
ERROR:
ORA-04043: object test1.t1 does not exist
--尝试无密码直接激活role user1_role
SQL> set role user1_role ;
set role user1_role
*
ERROR at line 1:
ORA-01979: missing or invalid password for role 'USER1_ROLE'
--使用密码激活role user1_role
SQL> set role user1_role identified by test1;
Role set.
SQL> select *from session_roles;
ROLE
------------------------------
USER1_ROLE
SQL> desc test1.t1
Name Null? Type
----------------------------------------- -------- ----------------------------
OBJECT_NAME VARCHAR2(128)
SUBOBJECT_NAME VARCHAR2(30)
OBJECT_ID NUMBER
DATA_OBJECT_ID NUMBER
OBJECT_TYPE VARCHAR2(19)
CREATED DATE
LAST_DDL_TIME DATE
TIMESTAMP VARCHAR2(19)
STATUS VARCHAR2(7)
TEMPORARY VARCHAR2(1)
GENERATED VARCHAR2(1)
SECONDARY VARCHAR2(1)
使用另外一个session，使用同样的账号test3
SQL> conn test3/test3
Connected.
SQL> select *from session_roles;
ROLE
------------------------------
CONNECT
SQL> set role user2_role identified by test2;
Role set.
SQL> desc test1.t2
Name Null? Type
----------------------------------------- -------- ----------------------------
TNAME NOT NULL VARCHAR2(30)
TABTYPE VARCHAR2(7)
CLUSTERID NUMBER
secure application role
关于secure applicaton role可以是对role的高级使用，比如你可以限制某些Ip的机器才能激活某些权限。某些特定条件的用户才能激活某些权限，甚至指定在每天的每个时间段才能激活某些权限。这些复杂的需求直接通过external role，dbms_session.set_role, set role等操作就不能实现，需要更细粒度的控制。
下面就举一个例子，来让指定的用户才能激活某些权限。
SQL> select *from all_users;
USERNAME USER_ID CREATED
------------------------------ ---------- ---------
DIP 20 06-NOV-13
TSMSYS 22 06-NOV-13
TEST1 26 07-NOV-13
TEST2 30 10-NOV-13
DBSNMP 25 07-NOV-13
SYS 0 06-NOV-13
SYSTEM 5 06-NOV-13
OUTLN 11 06-NOV-13
8 rows selected.
test1下有个表mv_test， 只能通过用户test2才能访问。
(注意：要实现这个需求，如果对于dba账户来说没有任何限制，因为dba账户本来就可以访问test1.mv_test)
步骤如下：
创建role,指定通过内嵌dbms_session.set_role的包来激活
SQL> conn test1/test1
Connected.
SQL> create role r1 identified using test1.setroles;
Role created.
SQL> grant select on test1.mv_test to r1;
Grant succeeded
SQL> grant r1 to test2;
Grant succeeded.
--注意一定要制定authid current_user
SQL> create or replace package setroles authid current_user as
2 procedure setrole;
3 end;
4 /
Package created.
--创建包体
SQL> create or replace package body setroles as
2 procedure setrole as
3 begin
4 if(sys_context('USERENV','current_user')='TEST2') then
5 dbms_session.set_role('R1');
6 end if;
7 end;
8 end;
9 /
--如果可以，可以把运行这个包的权限开放，但是只有合适的用户才能激活。
SQL> grant execute on test1.setroles to public;
--用测试用户连入
SQL> conn test2/test2
Connected.
--查看当前持有的role
SQL> select *from session_roles;
ROLE
------------------------------
CONNECT
RESOURCE
SQL> desc test1.mv_test
ERROR:
ORA-04043: object test1.mv_test does not exist
--运行指定的包以后，来验证
SQL> exec test1.setroles.setrole;
PL/SQL procedure successfully completed.
SQL> select *from session_roles;
ROLE
------------------------------
R1
SQL> desc test1.mv_test
Name Null? Type
----------------------------------------- -------- ----------------------------
OBJECT_ID NOT NULL NUMBER
OBJECT_NAME NOT NULL VARCHAR2(30)
CREATED NOT NULL DATE
选择另外一个用户来比较
--新创建一个用户。
SQL> conn / as sysdba
Connected.
SQL> create user test3 identified by test3;
User created.
SQL> grant connect,resource to test3;
Grant succeeded.
SQL> conn test3/test3
Connected.
SQL> select *from session_roles;
ROLE
------------------------------
CONNECT
RESOURCE
SQL> desc test1.mv_test
ERROR:
ORA-04043: object test1.mv_test does not exist
--运行指定的包，来验证。
SQL> exec test1.setroles.setrole;
PL/SQL procedure successfully completed.
SQL> select *from session_roles;
ROLE
------------------------------
CONNECT
RESOURCE
SQL> desc test1.mv_test
ERROR:
ORA-04043: object test1.mv_test does not exist
还有像external role,global之类的role可能使用不是很广泛，先说到这。后面后加以补充。
