Which customers have both "On Road" and "Shipped" as order status? List the customer ids.
select t1.customer_id from customers as t1 join orders as t2 on t1.customer_id = t2.customer_id where t2.order_status = "On Road" intersect select t1.customer_id from customers as t1 join orders as t2 on t1.customer_id = t2.customer_id where t2.order_status = "Shipped"