Question

使用此查询：

select C.CustomerID, P.ProductName, count(*) as Ordered
from Customers as C

join Orders as O on C.CustomerID = O.CustomerID
join [Order Details] as OD on O.OrderID = OD.OrderID
join Products as P on OD.ProductID = P.ProductID

group by C.CustomerID, P.ProductName

我可以选择客户购买的产品名称和订购

CustomerID|ProductName |Ordered
--------------------------------
ANTON     |Alice Mutton|1
BERGS     |Alice Mutton|1
BLONP     |Alice Mutton|1
BOLID     |Alice Mutton|1
BONAP     |Alice Mutton|1

使用这个：

select P.ProductName, count(*) as Ordered
from Products as P
join [Order Details] as OD on P.ProductID = OD.ProductID

group by P.ProductName

我可以选择每件产品的订购次数：

ProductName      |Ordered
-------------------------
Alice Mutton     |37
Aniseed Syrup    |12
Boston Crab Meat |41
Camembert Pierrot|51
Carnarvon Tigers |27

现在，我想将两个查询结合起来。我想看看单个客户订购了多少产品，以及该产品的订单总量是多少。我怎么能在一个查询中做到这一点？

Answer 1

你在寻找这样的东西吗？：

select a.*, b.ordered from (
select C.CustomerID, P.ProductName, count(*) as Ordered
from Customers as C
join Orders as O on C.CustomerID = O.CustomerID
join [Order Details] as OD on O.OrderID = OD.OrderID
join Products as P on OD.ProductID = P.ProductID
group by C.CustomerID, P.ProductName)a
left join
(select P.ProductName, count(*) as Ordered
from Products as P
join [Order Details] as OD on P.ProductID = OD.ProductID
group by P.ProductName)b
on a.ProductName=b.ProductName

Answer 2

对此：

select C.CustomerID, P.ProductName, count(*) as Ordered
from Customers as C

join Orders as O on C.CustomerID = O.CustomerID
join [Order Details] as OD on O.OrderID = OD.OrderID
join Products as P on OD.ProductID = P.ProductID

group by C.CustomerID, P.ProductName

添加如下内容：

union

select sum(0) as CustomerID, P.ProductName, count(*) as Ordered
from Orders as O 
join [Order Details] as OD on O.OrderID = OD.OrderID
join Products as P on OD.ProductID = P.ProductID

group by P.ProductName

Answer 3

基本上，您可以将总订单和客户订单的项目放入临时表，然后加入它们，如下所示。我选择了Name加入，但这可能需要调整，很难说。我喜欢这些不仅仅是子查询，我认为它们通常更快，但你也可以在连接中进行子查询。类似的概念。这可能不会给你你想要的最终结果，但希望它会给你一个良好的开端。

cat
dog
rabbit

如何将两个查询合并为一个

3 个答案: