SELECT a.cust_name, b.order_num
FROM Customers a
INNER JOIN Orders b
ON a.cust_id = b.cust_id
ORDER BY a.cust_name, b.order_num

思路：

1.查询顾客名称，来源于表a

2.查询订单号，来源于表b

3.根据用户id联结表