How to check Session memory For a Oracle User

To check the Memory Usage for Each Seesion :

    select username,name,value
    from v$session join v$sesstat using (sid)
    join v$statname using (statistic#)
    where name = 'session pga memory' and username='';


Example :

USERNAME                   NAME                                  VALUE
-----------------------------------------------------------      ----------
SCDB                       session pga memory                    699884

SCDB                       session pga memory                    651376

Thanks.
NJ