with x as (
   select
     tid
    ,regexp_substr(tid,'\d+',1,1) xidusn
    ,regexp_substr(tid,'\d+',1,2) xidslot
    ,regexp_substr(tid,'\d+',1,3) xidsqn
   from (select dbms_transaction.local_transaction_id tid from dual)
)
select *
from x, v$transaction t
where x.xidusn  = t.xidusn
  and x.xidslot = t.xidslot
  and x.xidsqn  = t.xidsqn;

select sid,username, tr.*
from v$session s, v$transaction tr
where tr.SES_ADDR = s.saddr