create or replace procedure Collapse is
teln1 tel_tmp.tl_n%type;
telk1 tel_tmp.tl_k%type;
teln2 tel_tmp.tl_n%type;
telk2 tel_tmp.tl_k%type;
idf1 tel_tmp.id_fao%type;
idf2 tel_tmp.id_fao%type;
cursor tmp is select distinct * from tel_tmp order by tl_n;

-- tel_tmp = исходная таблица (интервалы не свернуты)
-- telefons = итоговая таблица (интервалы свернуты)
-- tl_n = начало интервала; tl_k = конец интервала

begin

  delete from telefons;
  commit;
  
  open tmp;
  fetch tmp into teln1,telk1,idf1;
  
  loop
  begin
    fetch tmp into teln2,telk2,idf2;    
    exit when tmp%notfound;
    if (teln2-telk1)<= 1  then
      if telk1<=telk2 then
       telk1:=telk2;
      end if;
    else
      insert into telefons(tl_n,tl_k,id_fao) values (teln1,telk1,idf1);
      teln1:=teln2;
      telk1:=telk2;
      idf1:=idf2;
    end if; 
  end;
  end loop;

  close tmp;
  
  insert into telefons(tl_n,tl_k,id_fao) values (teln1,telk1,idf1);  
  commit;
  
exception
   when others then
     sys.dbms_output.put_line('No data found');
    
end Collapse;