How to recreate DBA roles if accidentally drop?

VERSION 7.X:   From Server Manager, logged in as internal or sys, run the following commands:

         SVRMGRL > create role dba;
        SVRMGRL > grant all privileges to dba with admin option;

VERSION 8.X:   From SQL*Plus or Server Manager, logged in as internal or sys, run the   following commands:   

SQL > create role dba;       
SQL > grant all privileges to dba with admin option;       
SQL > grant select_catalog_role to dba with admin option;       
SQL > grant execute_catalog_role to dba with admin option;       
SQL > grant delete_catalog_role to dba with admin option;

Explanation:  ============    
The DBA role is created at database creation time by the “sql.bsq” script. (The “sql.bsq” script is typically found in the $ORACLE_HOME/dbs or the $ORACLE_HOME/rdbms/admin directory.)  Additional grants are made to dba through other scripts in the admin directory.  For example, exp_full_database  and imp_full_database in catexp.sql.

Note : Version 8.X will works On 10g , 11g

Thank you
Osama mustafa