create or replace trigger logon_audit_trigger
  AFTER LOGON ON DATABASE
BEGIN
  insert into audit_acces
  values
    (user,
     sys_context('USERENV', 'SESSIONID'),
     sys_context('USERENV', 'HOST'),
     null,
     null,
     null,
     sysdate,
     to_char(sysdate, 'hh24:mi:ss'),
     null,
     null,
     null);
END;
/