Currently Connected Users
 
SELECT SUBSTR(v_$session.USERNAME,1,15) USERNAME,
SUBSTR(s.status,1,8) STATUS,
SUBSTR(s.server,1,10) SERVER,
SUBSTR(s.TYPE,1,10) TYPE,
SUBSTR(s.event,1,20) "WAIT EVENT",
DECODE(s.command,
       1,'Create Table',
       2,'Insert',
       3,'Select',
       6,'Update',
       7,'Delete',
       8,'Drop',
       9,'Create Index',
      10,'Drop Index',
      12,'Drop Table',
      17,'Grant',
      26,'Lock Table',
      42,'Alter Session',
      43,'Alter User',
      44,'Commit',
      45,'Rollback',
      s.command) COMMAND
FROM v_$session s, v_$session_wait w
WHERE (s.sid = w.sid)
AND s.username != 'SYS'
ORDER BY s.username;