About User Privileges and Roles

User privileges provide a basic level of database security. They are designed to control user access to data and to limit the kinds of SQL statements that users can execute. When creating a user, you grant privileges to enable the user to connect to the database, to run queries and make updates, to create schema objects, and more. There are two main types of user privileges:

System privileges—A sys tem privilege gives a user the ability to perform a particular action, or to perform an action on any schema objects of a particular type. For example, the system privilege CREATE TABLE permits a user to create tables in the schema associated with that user, and the system privilege CREATE USER permits a user to create database users.
Object privileges—An obje ct privilege gives a user the ability to perform a particular action on a specific schema object. Different object privileges are available for different types of schema objects. The privilege to select rows from the EMPLOYEES table or to delete rows from the DEPARTMENTS table are examples of object privileges.

Mana ging privileges is made easier by using roles, which are named groups of related privileges. You create roles, grant system and object privileges to the roles, and then grant roles to users. You can also grant roles to other roles. Unlike schema objects, roles are not contained in any schema.

Table 7-1 lists three widely used roles that are predefined in Oracle Database. You can grant these roles when you create a user or at any time thereafter.

Table 7-1 Oracle Database Predefined Roles

Role Name	Description
`CONNECT`	Enables a user to connect to the database. Grant this role to any user or application that needs database access. If you create a user using Oracle Enterprise Manager Database Control, this role is automatically granted to the user.
`RESOURCE`	Enables a user to create, modify, and delete certain types of schema objects in the schema associated with that user. Grant this role only to developers and to other users that must create schema objects. This role grants a subset of the create object system privileges. For example, it grants the `CREATE` `TABLE` system privilege, but does not grant the `CREATE` `VIEW` system privilege. It grants only the following privileges: `CREATE` `CLUSTER`, `CREATE` `INDEXTYPE`, `CREATE` `OPERATOR`, `CREATE` `PROCEDURE`, `CREATE` `SEQUENCE`, `CREATE` `TABLE`, `CREATE` `TRIGGER`, `CREATE` `TYPE`. In addition, this role grants the `UNLIMITED` `TABLESPACE` system privilege, which effectively assigns a space usage quota of `UNLIMITED` on all tablespaces in which the user creates schema objects.
`DBA`	Enables a user to perform most administrative functions, including creating users and granting privileges; creating and granting roles; creating, modifying, and deleting schema objects in any schema; and more. It grants all system privileges, but does not include the privileges to start up or shut down the database. It is by default granted to users `SYS` and `SYSTEM`.