Database Administrator Users:

- Two database user accounts, SYS and SYSTEM, are created automatically with the database and granted the DBA role.

- The DBA role has all database system privileges.

- SYS : Owner of the database data dictionary.

- SYSTEM : Owner of additional internal tables and views used by Oracle tools

Authentication Methods for Database Administrators:

- operating system authentication

- password files to authenticate database administrators.

Using Password File Authentication:

Delete the existing password file and create a new password file by using the Oracle password utility. Setup:

1.Create the password file using the password utility orapwd

Syntax:

orapwd file=filename password=password entries=max_users force=y|n

Where:

- filename is the name of the password file

- password is the password for SYSOPER and SYSDBA

- entries is the maximum number of distinct users allowed to connect as SYSDBA or SYSOPER.

If you exceed this number, you must create a new password file. It is safer to have a larger number.

- force option is judging that It has the same file , if have , y means cover it ,n means don't do anything! new feature in 10g.

2.Set the REMOTE_LOGIN_PASSWORDFILE parameter to EXCLUSIVE or SHARED

ALTER SYSTEM SET REMOTE_LOGIN_PASSWORDFILE=EXCLUSIVE SCOPE = SPFILE;

- EXCLUSIVE indicates that only one instance can use the password file and that the password file contains names other than SYS.

Using an EXCLUSIVE password file you can grant SYSDBA or SYSOPER privileges to individual users.

- SHARED indicates that more than one instance can use the password file.

The only user recognized by the password file is SYS. You cannot add users to the SHARED password file.

3.Add users to the password file and assign appropriate privileges to each user

eg:GRANT SYSDBA TO HR;

When you connect using SYSDBA privilege, you are connecting as SYS schema and not the schema associated with your username.For SYSOPER, you are connected to the PUBLIC schema.

DBA Tools:

The standard applications that are supplied with Oracle Enterprise Manager include the following:

- Instance Manager: Performs startup, shutdown and monitor databases

- Security Manager: Used to manage users and privileges

- Storage Manager: Maintains tablespaces, data files, rollback segments and log groups

- Schema Manager: Used to create and maintain objects such as tables, indexes, and views

- SQL*Plus Worksheet: Provides the capability to issue SQL statements against anydatabase