use of trigger within in a procedure

[bj]

Hi all,
Let say I have a table with data like this:

id id2 id3
100 12.5
200 13.5
300 15.4

Now What I want to do is update the id column with a sequance(start from 1). I know I could write a trigger on this table but my question is I'm not updatating anything else in within the procedure only the id column. So I am not sure I could do this within a procedure. How can I achive this?

Thanks,