How to write a Query which group data by holes?

[Jensan Lo]

Hi all,

I am having a problem with writting a query.
Sample Data:
ID
1
2
4
5
6
9
10

I am trying to group the data by the "holes", so that the output would be:
ID----Group
1-------1
2-------1
4-------2
5-------2
6-------2
9-------3
10-----3

Is it possible to have something like this in one query?
I am using mySQL 4.0 and therefore no stored procedures can be used.

Thank you!