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