Drupal - Select and update all users by role

gistfile1.txt

<?php 
// Select and update user by role
$role = user_role_load_by_name('blogger');
$query = 'SELECT ur.uid FROM {users_roles} AS ur WHERE ur.rid = :rid';
$result = db_query($query, array(':rid' => $role->rid));
$uids = $result->fetchCol();
$users = user_load_multiple($uids);
foreach($users as $user) {
   // $user->field_to_update['und'][0]['value'] = 1;
   // user_save($user);
   dpm($user);
}