inspect Oracle active sessions

Here come queries useful to see the current running sessions, together with the sql being executed and the associated events

select u.username, ash.session_id, ash.session_serial#, ash.event, count(*), ash.SQL_ID, s.sql_text
      from gv$active_session_history ash, v$sql s, V$SESSION u
      where ash.sql_id=s.sql_id and u.user# = ash.user_id
    group by ash.session_id, ash.session_serial#, u.username, ash.SQL_ID, ash.event, sql_text
    order by 1;

select se.username, se.sid, se.serial#, sq.sql_fulltext
      from V$SESSION se, v$sql sq
      where se.sql_id = sq.sql_id
order by 1