database - Grant permission from one user to another in Oracle -

i want know how grant permission of database objects particular user has access to user.

to illustrate, there 4 users in oracle database: a, b, c, , d.

1. user not own objects, has access objects in b , c.
2. users b , c own objects, have access other database objects in b, c, , d.

now want user have privileges user b , c have (some of them have already).

what proper way this. should use query or procedure? should procedure run login of database object owner? example, b has access object in d, can b give grant permission of d's object a?

you can group system , object privileges using roles , assign roles users , other roles. way can grant privileges roles contain users en masse, simplifies security administration (see "privilege , role authorization" in database concepts).

for example, b has access object in d, can b give grant permission of d's object a?

the user scott can grant object privilege, system privilege, or role user or role if has been granted privilege or role with admin option or with grant option. example, role select_hr has privileges query tables owned user hr:

create role select_hr; grant select on hr.employees select_hr; grant select on hr.departments select_hr; 

now can assign role scott way:

grant select_hr scott admin option; 

scott able assign role other database users or without admin option:

grant select_hr bob; 

see "granting user privileges , roles" in database security guide.