How to show age_range from Facebook Graph API PHP - php

Question

I want to build a Login system with Facebook. And I want to get age_range from it.
Code is successfully to show id, username, etc. But not show age_range.
How to show age_range?
Here is my code
$user_profile = $facebook->api('/me?fields=id,first_name,last_name,email,gender,locale,picture,age_range');
$user = new Users();
$user_data = $user->checkUser('facebook',$user_profile['id'],$user_profile['first_name'],$user_profile['last_name'],$user_profile['email'],$user_profile['gender'],$user_profile['locale'],$user_profile['picture']['data']['url'],$user_profile['age_range']);
if(!empty($user_data)){
$output = '<h1>Facebook Profile Details </h1>';
$output .= '<img src="'.$user_data['picture'].'">';
$output .= '<br/>Facebook ID : ' . $user_data['oauth_uid'];
$output .= '<br/>Name : ' . $user_data['fname'].' '.$user_data['lname'];
$output .= '<br/>Email : ' . $user_data['email'];
$output .= '<br/>Usia : ' . $user_data['age_range'];
$output .= '<br/>Gender : ' . $user_data['gender'];
$output .= '<br/>Locale : ' . $user_data['locale'];
$output .= '<br/>You are login with : Facebook';
$output .= '<br/>Logout from Facebook';
Sorry, this is function of checkUser:
function checkUser($oauth_provider,$oauth_uid,$fname,$lname,$email,$gender,$locale,$picture){
$prev_query = mysqli_query($this->connect,"SELECT * FROM ".$this->table_name." WHERE oauth_provider = '".$oauth_provider."' AND oauth_uid = '".$oauth_uid."'") or die(mysql_error($this->connect));
if(mysqli_num_rows($prev_query)>0){
$update = mysqli_query($this->connect,"UPDATE $this->table_name SET oauth_provider = '".$oauth_provider."', oauth_uid = '".$oauth_uid."', fname = '".$fname."', lname = '".$lname."', email = '".$email."', gender = '".$gender."', locale = '".$locale."', picture = '".$picture."', modified = '".date("Y-m-d H:i:s")."' WHERE oauth_provider = '".$oauth_provider."' AND oauth_uid = '".$oauth_uid."'");
}else{
$insert = mysqli_query($this->connect,"INSERT INTO $this->table_name SET oauth_provider = '".$oauth_provider."', oauth_uid = '".$oauth_uid."', fname = '".$fname."', lname = '".$lname."', email = '".$email."', gender = '".$gender."', locale = '".$locale."', picture = '".$picture."', created = '".date("Y-m-d H:i:s")."', modified = '".date("Y-m-d H:i:s")."'");
}
$query = mysqli_query($this->connect,"SELECT * FROM $this->table_name WHERE oauth_provider = '".$oauth_provider."' AND oauth_uid = '".$oauth_uid."'");
$result = mysqli_fetch_array($query);
return $result;
}