SQL查询以选择总数的百分比

Question

我有一个 MSSQL 表存储，表中有以下列：

Storeid, NumEmployees
1       125 
2       154
3       10 
4       698
5       54  
6       98
7       87
8       100
9       58
10      897

有人可以帮助我使用 SQL 查询来生成占员工总数 (NumEmployees) 30% 的顶级商店 (storeID) 吗？

Answer 1

WITH cte 
     AS (SELECT storeid, 
                numemployees, 
                ( numemployees * 100 ) / SUM(numemployees) OVER (PARTITION BY 1) 
                AS 
                percentofstores 
         FROM   stores) 
SELECT * 
FROM   cte 
WHERE  percentofstores >= 30 
ORDER BY numemployees desc

Working Demo

不使用 SUM/OVER 的替代方案

SELECT s.storeid, s.numemployees 
FROM   (SELECT SUM(numemployees) AS [tots] 
        FROM   stores) AS t, 
       stores s 
WHERE  CAST(numemployees AS DECIMAL(15, 5)) / tots >= .3 
ORDER BY s.numemployees desc

Working Demo

请注意，在第二个版本中，我决定在除之前不乘以 100。这需要强制转换为十进制，否则它将被隐式转换为 int 导致不返回任何记录

另外，我不完全清楚您是否想要这个，但您可以将 TOP 1 添加到两个查询中，这会将结果限制为具有最多商店数量且超过 30% 的结果

更新

根据您的 cmets，听起来可以解释为 Kevin

你想要这些行，从员工最多的商店开始，一直到至少有 30% 的商店

这很困难，因为它需要一个运行百分比和一个装箱问题，但这确实有效。请注意，我已经包含了另外两个测试用例（其中百分比完全等于并且刚好超过前两个的总和）

Working Demo

DECLARE @percent DECIMAL (20, 16) 

SET @percent = 0.3
--Other test values
--SET @percent = 0.6992547128452433
--SET @percent = 0.6992547128452434 

;WITH sums 
     AS (SELECT DISTINCT s.storeid, 
                         s.numemployees, 
                         s.numemployees + Coalesce(SUM(s2.numemployees) OVER ( 
                                                   PARTITION 
                                                   BY 
                                                   s.numemployees), 0) 
                         runningsum 
         FROM   stores s 
                LEFT JOIN stores s2 
                  ON s.numemployees < s2.numemployees), 
     percents 
     AS (SELECT storeid, 
                numemployees, 
                runningsum, 
                CAST(runningsum AS DECIMAL(15, 5)) / tots.total 
                running_percent, 
                Row_number() OVER (ORDER BY runningsum, storeid ) rn 
         FROM   sums, 
                (SELECT SUM(numemployees) total 
                 FROM   stores) AS tots) 
SELECT p.storeID,
       p.numemployees,
       p.running_percent,
       p.running_percent,
       p.rn 
FROM   percents p 
       CROSS JOIN (SELECT MAX(rn) rn 
                  FROM   percents 
                  WHERE  running_percent = @percent) exactpercent 

       LEFT JOIN (SELECT MAX(rn) rn 
                   FROM   percents 
                   WHERE  running_percent <= @percent) underpercent 
         ON p.rn <= underpercent.rn 
             OR ( exactpercent.rn IS NULL 
                  AND p.rn <= underpercent.rn + 1 ) 
WHERE 
      underpercent.rn is not null or p.rn = 1