Freeradius + MySQL + WiFi PEAP authorisation only to a group of users

[Lumir Lindovsky]

Lumir Lindovsky wrote:
>> How do I give access to wifi users who authenticate with username&  pass
>> over PEAP only to a group of users?
>    See the FAQ.  You can create a group, and limit them based on group
> membership.  You can use SQL-Group.  See doc/rlm_sql
>
>    Alan DeKok.
> -
> List info/subscribe/unsubscribe? See http://www.freeradius.org/list/users.html
>
And could you plz give me a short example? And where to put the sql condition? In sql.conf or in eap.conf or in one of the site-enabled servers?
It should be in the authorise or authenticate section?
Users are stored in radcheck and users + groups associated to them are in radusergroup.
I did not find any example on the net or in the config.
Sorry for bothering but examples always help me most.
Thank you,
Lumir Lindovsky