如何用Laravel编写以下原始查询
$result= DB::select('SELECT a.awb_number,a.full_awb_number,a.service_type, b.city AS From_city, c.country_code AS From_country, b.city AS To_city, c.country_code AS To_country, datediff( max(s.created_at), min(s.created_at)) as Aging FROM customer_shippments a LEFT JOIN addr