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我正在尝试为 mySql 中的每个组选择百分比值。

我试图在内存中进行，但要维护很多代码。如果我通过 SQL 来做，那就太好了。

我正在选择以下数据：

Gender,Category,Month,Year,NumberOfCustomers
'female','Feature Phones','1','2019','1000'
'male','Feature Phones','1','2019','10000'
'female','Smart Phones','1','2019','30000'
'male','Smart Phones','1','2019','200000'
'female','Feature Phones','2','2019','20000'
'male','Feature Phones','2','2019','15000'
'female','Smart Phones','2','2019','30000'
'male','Smart Phones','2','2019','150000'

使用查询：

SELECT gender, category, month, year, 
SUM(number_of_customers) AS numberOfCustomers
FROM customer_table 
WHERE brand_id IN (100) 
AND category in (1,2)        
AND month in (1,2) and year in (2019)
GROUP BY month, year, category, gender;

我想要的是每个月的客户百分比。前任：

Gender,Category,Month,Year,NumberOfCustomers,PercentageCustomersPerMonth
'female','Feature Phones','1','2019',5000,2.04
'male','Feature Phones','1','2019',10000,4.08
'female','Smart Phones','1','2019',30000,12.24
'male','Smart Phones','1','2019',200000,81.63
'female','Feature Phones','2','2019',20000,9.30
'male','Feature Phones','2','2019',15000,6.97
'female','Smart Phones','2','2019',30000,13.95
'male','Smart Phones','2','2019',150000,69.76

有没有办法轻松做到这一点？提前非常感谢。

4

2 回答 2

3

您可以使用窗口函数：

SELECT gender, category, month, year, 
       SUM(number_of_customers) AS numberOfCustomers,
       (SUM(number_of_customers) /
        SUM(SUM(number_of_customers)) OVER (PARTITION BY year, month)
       ) as month_ratio
FROM customer_table 
WHERE brand_id IN (100) AND
      category in (1,2) AND   
      month in (1, 2) AND
      year in (2019)
GROUP BY month, year, category, gender;
于 2019-10-20T02:50:59.780 回答
2

如果您无权访问窗口函数，您可以查看每月和每年的总客户表，并从中计算百分比JOIN：customer_table

SELECT c.*, 
       c.NumberOfCustomers / t.TotalCustomers * 100 AS PercentageCustomersPerMonth
FROM customer_table c
JOIN (SELECT Month, Year, SUM(NumberOfCustomers) AS TotalCustomers
      FROM customer_table
      GROUP BY Month, Year) t ON c.Month = t.Month AND c.Year = t.Year

输出：

Gender  Category        Month   Year    NumberOfCustomers   PercentageCustomersPerMonth
female  Feature Phones  1       2019    1000                0.4149
male    Feature Phones  1       2019    10000               4.1494
female  Smart Phones    1       2019    30000               12.4481
male    Smart Phones    1       2019    200000              82.9876
female  Feature Phones  2       2019    20000               9.3023
male    Feature Phones  2       2019    15000               6.9767
female  Smart Phones    2       2019    30000               13.9535
male    Smart Phones    2       2019    150000              69.7674

dbfiddle 上的演示

于 2019-10-20T02:56:01.680 回答