我迄今为止已经使用了两个表的连接,但现在我想要连接三个表,如下图所示:
(来源:microsoft.com)
我已经尝试过连接两个表,
SELECT O.OrderID,O.CustID,O.OrderTotal,C.Name from Orders
as O inner join Customers as C on O.CustID=C.CustID
如何将第三个表与此表连接?有什么建议吗?
我迄今为止已经使用了两个表的连接,但现在我想要连接三个表,如下图所示:
(来源:microsoft.com)
我已经尝试过连接两个表,
SELECT O.OrderID,O.CustID,O.OrderTotal,C.Name from Orders
as O inner join Customers as C on O.CustID=C.CustID
SELECT O.OrderID,O.CustID,O.OrderTotal,C.Name, OC.OrderAmount
FROM Orders as O
INNER JOIN Customers as C
ON O.CustID=C.CustID
INNER JOIN OrderItems as OC
ON O.OrderID=OC.OrderID
Select Customers.Name
From OrderItems -- (Table 1)
INNER JOIN Orders -- (Table 2)
ON OrderItems.OrderID = Orders.OrderID
INNER JOIN Customers -- (Table 3)
ON Orders.CustID = Customers.CustID
Where Customers.CustID = 2 -- This will give you the name of the second customer in the third table using JOINS
inner join OrderItems as OI ON O.OrderID= OI.OrderID
Orders
中的OrderTotal
) - user57508SUM()
函数。 - user57508