How to retrieve the last updated information in each row

I have the table that is shown down below and have to retrieve the last updated code of the num, which I know by the date, but I don't really know how to retrieve that..

One method uses window functions:

select t.*
from (select t.*,
             row_number() over (partition by num order by created desc) as seqnum
      from t
     ) t
where seqnum = 1;

An alternative method that is often a bit faster with the right indexing is:

select t.*
from t
where t.created = (select max(t2.created) from t t2 where t2.num = t.num);

The right indexing is (num, created).