OO ref in PL/SQL

create type b as object(
  n number,
  v varchar2(10)
);
/


create table b_ref_table (
  i     number,
  b_ref ref b
);

create table b_table (
  y     number,
  b_    b
);

insert into b_table values (5,b(5,'five'));

select * from b_table;


declare
  b_ b;
begin
  b_ := b(5,'five');
  insert into b_ref_table select b.i, ref(b.b_) from b_table;
end;
/

drop table b_table;
drop table b_ref_table;

drop type b;