SQL，获得每年最高的付款月份

Question

我目前有这个显示了每月金额的总和。我想从中获得的是显示每年最高金额的月份。

SELECT year(paymentDate), month(paymentDate) , SUM(amount) 
FROM classicmodels.payments
GROUP BY year(paymentDate), month(paymentDate)
ORDER BY paymentDate ASC; 

以下表格我只想显示每年获得最高金额的月份

Answer 1

为SUM(Amount)添加列别名ORDER BY <that alias> DESC并将TOP(1)添加到SELECT

Answer 2

您可以使用ROW_NUMBER：

SELECT y, m, amount
FROM (
   SELECT YEAR(paymentDate) AS y, MONTH(paymentDate) AS m, 
          amount,
          ROW_NUMBER() OVER (PARTITION BY YEAR(paymentDate) ORDER BY amount DESC) AS rn
FROM classicmodels.payments) AS t
WHERE t.rn = 1

注意：如果是绑定，查询将返回任意月份。要返回金额最大的所有月份，请使用RANK而不是ROW_NUMBER。

Answer 3

使用ROW_NUMBER()您可以根据您的条件为每条记录分配序列号，并选择序列为1的记录。 以下示例;

SELECT  *
FROM    (
    SELECT year(paymentDate) year_val, month(paymentDate) month_val, SUM(amount) amt_val,
            ROW_NUMBER() OVER(PARTITION BY year(paymentDate) ORDER BY SUM(amount) DESC) AS ROW_ORDER
    FROM classicmodels.payments
    GROUP BY year(paymentDate), month(paymentDate)
)   AS  D
WHERE   D.ROW_ORDER = 1

还有很多其他方法可以实现同样的目标。

和WHERE D.ROW_ORDER = n - 你将每年返回第n位。