Question

我是窗口函数的新手。这是原始的桌子，有4种水果。

fruit   quantity
orange  100
banana  27
banana  20
orange  5
melon   5
apple   1
banana  10
banana  4
banana  36
banana  86
banana  47
apple   32
banana  7
banana  5
banana  3

是否可以将其转换为每种水果构成一切总量的百分比？这就是我想要的：

fruit       total       percentage
apple       33          9%
banana      245         63%
orange      105         27%
melon       5           1%

以下是我尝试的代码，但它给了我一个错误：

SELECT fruit
, SUM(quantity) / SUM(quantity) OVER () * 100
FROM fruit_inventory
GROUP BY fruit

如果我撤消GROUP BY并删除第一个SUM(quantity)，那么我会得到多条看起来像这样的记录：

fruit   quantity    percentage
apple   1           0%
apple   32          8%
banana  27          7%
banana  20          5%
banana  10          3%
banana  4           1%
banana  36          9%
banana  86          22%
banana  47          12%
banana  7           2%
banana  5           1%
banana  3           1%
melon   5           1%
orange  100         26%
orange  5           1%

Answer 1

使用汇总return json;的窗口sum。

sum

Answer 2

我相信这是你正在寻找的：

declare @fruitbasket table
    (
     Fruit nvarchar(50),
     Quantity decimal(19, 5)
    );

insert  into @fruitbasket
        (Fruit, Quantity)
values  (N'orange', 100),
        (N'banana', 27),
        (N'banana', 20),
        (N'orange', 5),
        (N'melon', 5),
        (N'apple', 1),
        (N'banana', 10),
        (N'banana', 4),
        (N'banana', 36),
        (N'banana', 86),
        (N'banana', 47),
        (N'apple', 32),
        (N'banana', 7),
        (N'banana', 5),
        (N'banana', 3);

select  Fruit,
        sum(Quantity) as Quantity,
        sum(Quantity) / (
                         select sum(Quantity) as Total
                         from   @fruitbasket
                        ) * 100 as PercentageOfTotal
from    @fruitbasket
group by Fruit;

Answer 3

使用CTE（公用表表达式），您可以获得所需的结果。整体CTE确实具有更好的性能并且具有更好的可读性。

WITH cte AS
(
    SELECT DISTINCT 
        Fruit
        ,SUM(Quantity) OVER (PARTITION BY fruit ORDER BY fruit) AS sumProducts
        ,SUM(SUM(Quantity)) OVER ()  AS totalProducts
    FROM stackOverflow
    GROUP BY 
        Fruit
        ,Quantity
)
SELECT Fruit, CAST(sumProducts AS INT) AS sumProducts, CAST(100 * sumProducts / totalProducts AS DECIMAL(5,2)) AS percentage
FROM cte

我可以将PARTITION BY与GROUP BY子句一起使用吗？ SQL Server 2012

3 个答案: