help need with mysql statement in freeradius

Hi all, I am trying to do MAC insertion during post authentication section with the help of freeradius. Like during authentication section it will check in mysql database for MAC use option. If MAC use= 1 then if the user is login for the first time then grab the mac address from the login process and insert into database. If mac use is not enable i.e. MAC use=0 then go through normal process. Is is possible how can I do that? Thanks in advance