sql - Selecting region information of product in northwind

Question

I want to to do following in northwind database:

Display the Product Names of all products that were placed by customers in CA but I'm confused how to relate a product with customer.

Answer 1

根据我的回忆，您需要将products表加入orders,orderDetails和customers表以获取客户订购的产品列表CA：

select distinct p.ProductName
from customers c
inner join orders o
  on c.customerId = o.customerId
inner join orderDetails od
  on o.orderId = od.orderid
inner join products p
  on od.productid = p.productid
where c.Region = 'CA'

或者您可以使用EXISTS：

select p.ProductName
from products p
where exists (select od.productid
              from customers c
              inner join orders o
                on c.customerId = o.customerId
              inner join orderDetails od
                on o.orderId = od.orderid 
              where c.Region = 'CA'
                and p.productid = od.productid)

请参阅带有 两个查询示例的 SQL Fiddle 演示。

Answer 2

SELECT DISTINCT PRD.PRODUCTNAME 
FROM CUSTOMERS AS CUST
INNER JOIN ORDERS AS ORD
ON CUST.CUSTOMERID=ORD.CUSTOMERID
INNER JOIN [ORDER DETAILS] AS ORDDETAILS
ON ORD.ORDERID=ORDDETAILS.ORDERID
INNER JOIN PRODUCTS AS PRD
ON ORDDETAILS.PRODUCTID=PRD.PRODUCTID
WHERE CUST.REGION='CA'

要按产品名称升序列出结果，请将其添加到末尾

ORDER BY PRD.PRODUCTNAME ASC 

Answer 3

以下为我完成了这项工作

Select distinct Products.ProductName From Products 
Where Products.ProductID in 
 (Select [Order Details].ProductID From [Order Details] Where [Order Details].OrderID in(select Orders.OrderID from Orders where Orders.CustomerID in(select Customers.CustomerID from Customers where Customers.Region='CA')))
 order by Products.ProductName;

Answer 4

尝试这个：

Select o.pdt_name From orders o 
Where o.cust_no in 
 (Select c.cust_no From customers c Where c.state = 'CA')
order by o.pdt_name