PHP select random id from database

I want to select a random userid from this query where level = 1 (Normal user) and alive = Yes (User is alive and can play)

$getaid = $sql->query("SELECT userid FROM `users` WHERE `level`='1' AND `alive`='yes'");

I know I can use

$totalusers = mysql_num_rows($getaid);
$randomuserid = rand(1,$totalusers);

to select a random userid but in that code there's a chance that it select a user that is dead (alive = No) or a staff member (level >= 1). is there a better way I can select a random userid without a chance to grab staff members/dead members?