two select menu question

[zoliky]

I use mySQL 4.1
I have a PHP script that show two select menu.

First Menu   Second Menu 
========     =========== 
yo2lux
paul
zoli

The first menu show all users from mySQL table register
I press a button to put two users to Second Menu. I have a picture http://img62.imageshack.us/img62/1245/newimgns9.png

Now when I press on submit, my PHP script add all users from "Second Menu" (yo2lux, zoli) to group 2.

This is my table user2groups

uid   gid
===  === 
1      2
3      2

This mean:

user with id 1 (yo2lux) is added to group 2
user with id 3 (zoli) is added to group 2

Now I run again my PHP script. I see the two menu.
In first menu I want to see all users from table register without : yo2lux and zoli because this users already added to user2groups table.

Exist a solution to solve this problem ?
I appreciate any answer, and thank you very much !

[jheitz]

Well you want to display all users not in table user2groups and group 2. That can be done with a standard select something like:

SELECT * FROM users WHERE NOT EXISTS (SELECT 1 FROM user2groups WHERE users.uid=user2groups.uid AND user2groups.gid=2)