create table user_audit_log
(
  user_id          varchar2(30 byte),
  session_id       number(8),
  host             varchar2(30 byte),
  last_program     varchar2(48 byte),
  last_action      varchar2(32 byte),
  last_module      varchar2(32 byte),
  logon_ts         timestamp,
  logoff_ts        timestamp,
  elapsed_seconds  number
);

create or replace trigger logon_audit_trigger 
after logon on database
begin 
insert into user_audit_log values( 
   user, 
   sys_context('USERENV','SESSIONID'), 
   sys_context('USERENV','HOST'), 
   null, 
   null, 
   null, 
   current_timestamp, 
   null, 
   null 
); 
end;
/

create or replace trigger logoff_audit_trigger 
before logoff on database
begin 

    update user_audit_log 
    set last_action = (select action from v$session where sys_context('USERENV','SESSIONID') = audsid) 
    where sys_context('USERENV','SESSIONID') = session_id; 

    update user_audit_log 
    set last_program = (select program from v$session where sys_context('USERENV','SESSIONID') = audsid) 
    where sys_context('USERENV','SESSIONID') = session_id; 

    update user_audit_log 
    set last_module = (select module from v$session where sys_context('USERENV','SESSIONID') = audsid) 
    where sys_context('USERENV','SESSIONID') = session_id; 

    update user_audit_log 
    set logoff_ts = systimestamp 
    where sys_context('USERENV','SESSIONID') = session_id; 

    update user_audit_log 
    set elapsed_seconds = 
            extract(day from (logoff_ts - logon_ts)) * 24*60*60 + 
            extract(hour from (logoff_ts - logon_ts)) * 60*60 + 
            extract(minute from (logoff_ts - logon_ts)) * 60 + 
            extract(second from (logoff_ts - logon_ts)) 
    where sys_context('USERENV','SESSIONID') = session_id; 
end;
/