多表联接

原创于 2013-04-12 17:59:24 发布 · 519 阅读

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本文展示了如何使用SQL查询来分析美国客户的订单情况，包括订单数量和产品总数。通过连接Customers、Orders和OrderDetails表，筛选出美国地区的客户数据，并按客户ID进行分组和聚合，得出每个客户的订单数量和所购买产品的总数。

select  C.custid,count (distinct O.orderid) AS 'ORDER_Num',SUM(qty) AS 'Product_Num'
from Sales.Customers AS C
	JOIN Sales.Orders AS O
		on C.custid = O.custid
	JOIN Sales.OrderDetails AS D
		on O.orderid = D.orderid
where C.country = 'USA'
group by C.custid
order by c.custid