mysql - SQL - 行是否匹配总和的最大值

Question

我对 SQL 查询有点迷惑。这是一些背景。

架构:

Product(pid, price, color),
Order(cid, pid, quantity),
Customer(cid, name, age)

我想获取订购最多的产品(最大数量)的 pid。

我已经设法确定了最大值:

Select Max(total) 
From (Select Sum(quantity) as total 
      From Orders Group By pid) as Totals

但我在尝试匹配此子查询中的哪些产品时遇到了困难。这是我尝试过的:

Select pid, SUM(quantity) as q 
From Orders 
Where q in (
    Select Max(total) 
    From (Select Sum(quantity) as total 
          From Orders 
          Group By pid) as Totals
    ) 
Group By pid

这表示 q 是未知列。

关于我如何做到这一点或做得更好有什么建议吗？

Answer 1

你可以像GROUP BY一样做一个JOIN

select p.*
from product p
join
(select pid from Order
 group by pid having quantity = max(quantity)
) tab on p.pid = tab.pid;

在您发布的查询中它出错 q is an unknown column 因为 q 是您尝试在 WHERE 条件下使用的列别名;这是不允许的。