Finding the latest / max records in transactional table

Finding the latest / max records
I’ve just came up with aniother problem of getting a set of results. Finding the latest records, Example:

ID Mobileno created
1 +90990 01-FEB-06
2 +90990 02-FEB-06
3 +90991 02-FEB-06
4 +90991 01-FEB-06

The results must be like this , only 1 mobileno with the latest creation date

ID Mobileno created
2 +90990 02-FEB-06
3 +90991 02-FEB-06

The answer:
select t.*
from (select a.*,dense_rank() over (partition by mobileno order by created desc) dr from my_table a) t
where dr=1;