do $$ 
declare
    _list refcursor;
    _item record;
begin
    
    open _list for
        select *
        from tb_part
        where
            id_part > 2
        order by
            id_part desc;
                
    fetch _list into _item;
        
    while (found) loop
        update tb_part set
            id_part = _item.id_part * 100
        where
            id_part = _item.id_part;
        
        fetch _list into _item;
    end loop;

end $$;