selecting entire row on which one field is the minimum

Hi,

i have a table with 2 fields, let's say A and B, both integers.
i would like to select all the A for which the B are minimum

i'm not sure i am clear, so here is an exemple :

A | B
1 | 5
2 | 2
3 | 3
4 | 2
5 | 2

in this situation, the query should return (2, 4, 5)
as it is very easy to ordre a table, i tought this query would be easy
too, but it is more difficult than it looks like.

thanks for help

Edouard Boucher