Does anyone know anything about Oracle Roles & privileges. An application on 9i has multiple roles assigned to each user. I am getting permissions problems, I think because there are conflicting privileges within the roles. EG:

Role1 has SELECT, UPDATE on table1.
Role2 has SELECT, INSERT on table1.
User Default is set as (Role1,Role2).

I thought it would accumulate all the permissions for table1 but it appears to be overwriting Role1 with Role2 so I lose the UPDATE privilege.


That never happens. It seems you mis-understood the concept of Roles and privileges. In your case if the user has both the privileges ROLE1 and ROLE2 then the user will have
SELECT and INSERT and UPDATE on the table1.

one role will not over write to another it only adds to the privileges of the other existing/granted roles.