聚合顶部以外的行答案

【问题标题】：Aggregate rows outside the top聚合顶部以外的行
【发布时间】：2015-10-06 20:23:06
【问题描述】：

假设我们有以下 Fruits 表：

Fruit   | Qty
-------------
Apple   | 2
Apple   | 5
Apple   | 2
Orange  | 3
Orange  | 4
Orange  | 0
Banana  | 2
Banana  | 5
Pear    | 2
Mango   | 1
Mango   | 0

如果我想获得前 3 种水果，我会创建这样的查询：

SELECT TOP 3 Fruit, SUM(Qty) AS Total
FROM Fruits
GROUP BY Fruit
ORDER BY Total DESC

将返回：

Apple   | 9
Orange  | 7
Banana  | 7

但是，如果我想包括不在前 3 名中的水果的总和，我将不得不使用 NOT IN 编写类似这样的内容来排除前 3 名水果：

SELECT 'OTHER' AS Fruit, SUM(Qty) AS Total
FROM Fruits
WHERE Fruit NOT IN (SELECT Fruit FROM (SELECT TOP 3 Fruit, SUM(Qty) AS Total FROM Fruits GROUP BY Fruit ORDER BY Total DESC) AS Test)

如果我想在单个查询中执行此操作，我想我可以使用UNION 组合这两个查询。我已经有了我的计划 B，但我想知道 SQL 是否有任何内置方法来聚合不属于可用于简化查询的最高值的行？

【问题讨论】：

标签： sql sql-server aggregate sql-server-2014

【解决方案1】：

您需要对总和进行排名并为最终结果添加另一个 SUM：

with cte as
 (
   SELECT Fruit, SUM(Qty) AS Qty,
      ROW_NUMBER() OVER (ORDER BY SUM(Qty) DESC) AS rn
   FROM Fruits 
   GROUP BY Fruit
 )
select 
   case when rn > 3 then 'Other' else fruit end as fruit, 
   sum(Qty)
from cte
group by 
   case when rn > 3 then 'Other' else fruit end
order by MIN(rn)

见Fiddle

【讨论】：

【解决方案2】：

这是通过基于sum(qty) 对行进行排名的一种方法。

with totals as (SELECT Fruit, SUM(Qty) AS Total FROM Fruits GROUP BY Fruit)
, rownums as (select *, dense_rank() over(order by total desc) as rank from totals)
select 
case when rank > 3 then 'Other' else fruit end as fruit, total
from rownums

如果other 行需要聚合，请在total 列中再包含一个sum，并在group by 语句中包含group by。

【讨论】：

【解决方案3】：

几乎！，可惜你不能把排名放在一个拥有！但你不能。所以你必须有一个嵌套的选择，然后是一个位置。

加上这个方法，你可以得到任何你想要的组，即 BETWEEN 0 AND 3.. > 3 .. IN(1,3,6) 等

DECLARE @Fruits TABLE (Fruit NVARCHAR(32),Qty INT)
INSERT INTO @Fruits(Fruit,Qty)
VALUES
('Apple',2),
('Apple',5),
('Apple',2),
('Orange',3),
('Orange',4),
('Orange',0),
('Banana',2),
('Banana',5),
('Pear',2),
('Mango',1),
('Mango',0)

SELECT TOP 3 Fruit, SUM(Qty) AS Total
FROM @Fruits
GROUP BY Fruit
ORDER BY Total DESC

SELECT A.Fruit,A.Total FROM
(
    SELECT Fruit, SUM(Qty) AS Total,RANK() OVER (ORDER BY SUM(Qty) DESC,Fruit) AS GroupNumber
    FROM @Fruits
    GROUP BY Fruit
) AS A
WHERE GroupNumber > 3 --This bit lets you pick the groups!
ORDER BY Total DESC

【讨论】：