When writing json containing Arabic characters, they appear as question marks.
$con = mysqli_connect($host,$username,$password,$db);
$q = mysqli_query($con,'select `product_id`, `product_name`, `sku`, `price`, `final_price`, `minimal_price`, `special_price`, `image`, `small_image`, `thumb_image`, `short_description`, `href`, `is_favorite`, `category_name` from products_uae_ar');
mysqli_query($con, "SET NAMES 'utf8'");
mysqli_query($con, "SET CHARACTER SET 'utf8'");
print_r( json_encode($output));