SQL查询问题 - 在不使用AVG（）函数的情况下获得平均值 [英] SQL Query Question - getting average without using AVG() function

问题描述

我希望从以下查询中获取订单的平均值和订单商品的平均价值。我想以这种格式获得输出：

两列：订单平均值和 OrderItems平均值）或在一列中，每个输出都在自己的行中。我怎样才能做到这一点？谢谢。

I am looking to get the average value for orders, and average value for order items from the query below. I would like to get the output in this format:
two columns: "Orders Average" and "OrderItems Average") or in one column with each output in its own row. How can I do that? Thank you.

SELECT (COUNT(Orders.orderid) / SUM(Inventory.price)) AS Orders_Average,
(COUNT(OrderItems.orderid) / SUM(Inventory.price)) AS OrderItems_Average
FROM  ORDERITEMS LEFT OUTER JOIN
               Inventory ON OrderItems.partid = Inventory.partid RIGHT OUTER JOIN
               Orders ON OrderItems.orderid = Orders.orderid

推荐答案

平均计算的公式不应该相反？此外，看起来像INNER连接应该为你做。

Shouldn''t the formula be opposite for average calculation? Further, looks like an INNER join should do it for you.

SELECT 
   (SUM(Inventory.price) / COUNT(Orders.orderid)) AS Orders_Average,
   (SUM(Inventory.price) / COUNT(OrderItems.orderid)) AS OrderItems_Average
FROM  
    ORDERITEMS 
INNER JOIN
     Inventory ON OrderItems.partid = Inventory.partid 
INNER JOIN
     Orders ON OrderItems.orderid = Orders.orderid

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