SQL> select user#,name from user$ where name like 'SCO%';

USER#      NAME
---------- ------------------------------
59         SCOTT
64         SCOTT1

SQL> update user$ set name='HERMESNEW' where user#=64;

1 row updated.

SQL> commit;

Commit complete.

SQL> select user#,name from user$ where name like 'SCO%';

USER#      NAME
---------- ------------------------------
59         SCOTT

SQL> select user#,name from user$ where name like 'HER%';

USER#      NAME
---------- ------------------------------
65         HERMES
64         HERMESNEW

SQL> alter user hermesnew identified by chirag;

User altered.

SQL> conn hermesnew/chirag
ERROR:
ORA-01017: invalid username/password; logon denied


Warning: You are no longer connected to ORACLE.
SQL> select username from dba_users;
SP2-0640: Not connected
SQL> conn / as sysdba
Connected.

SQL> select username from dba_users where username like 'HE%';

USERNAME
------------------------------
HERMES