Reordering a table

Hi,

a puzzle to solve...

I have a table with a primary key, and a timestamp, e.g.

id    stamp
1     2011-02-01 10:00
2     2011-02-01 09:00
3     2011-02-01 11:00

Now for reasons too painful to go into, I need to reorder the id
(sequence) so that they are in time order:

id    stamp
1     2011-02-01 09:00
2     2011-02-01 10:00
3     2011-02-01 11:00

I thought I could do it by adding a third colum with the order in it,
but I cannot think of a way to do this short of writing some code

id    stamp                         order
1     2011-02-01 10:00    2
2     2011-02-01 09:00    1
3     2011-02-01 11:00    3

Any ideas?

Thanks.
Howard
www.selestial.com