对某些分组行求和

Question

我有一个数据集，显示每个类别的消费者（访问过一次、两次、三次、四次、五次等的消费者）的客人数量和收入。

看起来像这样：

我得到上述 table 的查询是：

SELECT number_of_trans, COUNT(*) AS guest_count, SUM(amount) AS revenue FROM customer_counting GROUP BY number_of_trans ORDER BY number_of_trans

现在，我想对 guest_count 和收入求和，我想对以下类别求和：1、2、3、4、5-7 和 8+。

所以实际上 1、2、3 和 4 将保持不变，但我将在第 5 - 7 行和第 8 行及以后的行中求和。

我该怎么做？我要的table如下（不要担心数值的准确性）：

希望我的问题得到理解。

Answer 1

使用 case 和子查询（或 CTE）：

SELECT (CASE WHEN number_of_trans < 5 THEN CAST(number_of_trans as varchar)
             WHEN number_of_trans < 8 THEN '5-7'
             ELSE '8+'
        END) as grp,
       SUM(guest_count) as guest_count, SUM(revenue) as revenue
FROM (SELECT number_of_trans, COUNT(*) AS guest_count, SUM(amount) AS revenue
      FROM customer_counting
      GROUP BY number_of_trans
     ) x
GROUP BY grp
ORDER BY MIN(number_of_trans);

Answer 2

戈登提议的更简单形式：

SELECT 
  CASE WHEN number_of_trans < 5 THEN cast(number_of_trans as varchar)
    WHEN number_of_trans < 8 THEN '5-7'
    ELSE '8+' 
  END as freq_band, 
  COUNT(*) AS guest_count, 
  SUM(amount) AS revenue 
FROM customer_counting 
GROUP BY CASE WHEN number_of_trans < 5 THEN cast(number_of_trans as varchar)
    WHEN number_of_trans < 8 THEN '5-7'
    ELSE '8+' 
  END
ORDER BY freq_band

对某些分组行求和

Sum Over Certain Grouped Rows

sql

presto