使用分组案例语句计算总数的百分比

Question

所以我有一个已分组的 CASE 语句。但是，我也试图计算每个 Grouped CASE 结果占总数的百分比。当我运行下面的命令时，它给出了

Region         Number  Percentage
West Coast     11675   0
Not West Coast 104620  0

我不明白为什么“百分比”为“0”。

这是代码，标有“问题行”。

With [Summed Region] AS
(

SELECT 
    [State Province],

    CASE [State Province]
    WHEN 'Oregon' THEN 'West Coast'
    WHEN 'Washington' THEN 'West Coast'
    WHEN 'California' THEN 'West Coast'
    ELSE 'Not West Coast'
    END AS 'Region'

FROM 
  [WideWorldImportersDW].[Dimension].[City]
)

SELECT 
    Region,
    count(Region) AS Number,
    ---THE PROBLEM LINE IS BELOW THIS---
    count(region)/(select count(*) FROM [WideWorldImportersDW].[Dimension].
    [City]) AS Percentage


FROM 
    [Summed Region]

GROUP BY
    Region

那条线有什么问题？如果我把这两部分分开，每一个都返回正确的数字。但是当我将一个除以另一个时，我得到“0”。

谢谢！

Answer 1

这称为整数除法。所以在某处添加一个小数：

SELECT Region, count(Region) AS Number,
       count(region) * 1.0 / (select count(*) FROM [WideWorldImportersDW].[Dimension].[City]) AS Percentage
FROM [Summed Region]
GROUP BY Region;

你也不需要子查询，所以使用窗口函数：

SELECT Region, count(*) AS Number,
       count(*) * 1.0 / sum(count(*)) over () AS Percentage
FROM [Summed Region]
GROUP BY Region;