ORACLE - How get sessionid

Every login in Oracle has our sessionid - you can use it for example for data inserted to table:

insert into factory.an_question_fort
( sessionid, tl_nr, tl_fam, tl_atn, bst_akt_mz, dat_neu )
values
( userenv( 'SESSIONID' ), pc_m.tl_nr, pc_m.tl_fam, pc_m.tl_atn, iInv, trunc( sysdate ) );