Change Character Set Oracle

SQL> shutdown IMMEDIATE;
SQL> startup restrict    /ALTER SYSTEM ENTABLE RESTRICTED SESSION;
SQL> SELECT name FROM v$database;
SQL> ALTER DATABASE CHARACTER SET INTERNAL_USE AL32UTF8;
SQL> SELECT VALUE FROM NLS_DATABASE_PARAMETERS WHERE parameter=’NLS_CHARACTERSET’;
SQL> shutdown IMMEDIATE;
SQL> startup
SQL> SELECT VALUE FROM NLS_DATABASE_PARAMETERS WHERE parameter=’NLS_CHARACTERSET’;
AL32UTF8
AMERICAN_AMERICA.WE8MSWIN1252