Enabling sql trace in OC4J & system wide

http://rreddy.blogspot.com/2006/09/enabling-sql-trace-in-oc4j.html

Select SID,SERIAL#,USERNAME,STATUS from v$session;

::Session level tracing::

exec dbms_system.set_ev( 375,501,10046,12.' ');
execute sys.dbms_system.set_ev(375,501, 10046, 12, '');
execute sys.dbms_system.set_ev(375,501, 10046, 0, '');

::System Wide SQL Tracing::

alter system set events '10046 trace name context forever,level 12';
alter system set events '10046 trace name context off';

For SYSTEM WIDE use this url:

http://www.orafaq.com/wiki/SQL_Trace