Sql 基于范围从同一表的两个不同列进行计数

我有这样的啤酒：

MONTHS  CUST    CATEGORY
10       1          1
20       2          1
10       3         NULL
30       4          1
40       5          NULL

我想根据范围统计客户数量和类别数量

例如：
在10-19范围内，客户数量为2，类别为1。

---

请提供帮助。

您可以使用如下查询：

SELECT CASE 
            WHEN MONTHS BETWEEN 10 AND 19 THEN '10-19'
            WHEN MONTHS BETWEEN 20 AND 29 THEN '20-29'
            WHEN MONTHS BETWEEN 30 AND 39 THEN '30-39'
            WHEN MONTHS BETWEEN 40 AND 49 THEN '40-49'
            ELSE '50-'
         END,
         COUNT(CUST) AS CUST_COUNT,
         COUNT(CATEGORY) AS CATEGORY_COUNT
FROM mytable
GROUP BY CASE 
            WHEN MONTHS BETWEEN 10 AND 19 THEN '10-19'
            WHEN MONTHS BETWEEN 20 AND 29 THEN '20-29'
            WHEN MONTHS BETWEEN 30 AND 39 THEN '30-39'
            WHEN MONTHS BETWEEN 40 AND 49 THEN '40-49'
            ELSE '50-'
         END

---

只要可以计算出在整个范围内产生相同值的分组表达式，就可以使用分组依据：

Select
     (MONTHS - (MONTHS % 10)) As RANGE
   , Count(CUST)              As CUST_COUNT,
   , Count(CATEGORY)          As CATEGORY_COUNT
From
     tbale --< :-)
Group By
     (MONTHS - (MONTHS % 10)); --< Expression that would result in the same value for the entire RANGE

选择
（月-（月%10））作为范围
，将（客户）计数为客户计数，
，将（类别）计数为类别计数
从…起
tbale——<：-）
分组
（月-（月%10））；——<表达式，该表达式将在整个范围内产生相同的值

Giorgos Betsos的答案调整为使用派生表。无需键入该

大小写

表达式两次。符合ANSI SQL（因为在

GROUP BY

子句中只允许列。）

select MONTHS, COUNT(CUST) AS CUST_COUNT, COUNT(CATEGORY) AS CATEGORY_COUNT
from
(
    SELECT CASE 
                WHEN MONTHS BETWEEN 10 AND 19 THEN '10-19'
                WHEN MONTHS BETWEEN 20 AND 29 THEN '20-29'
                WHEN MONTHS BETWEEN 30 AND 39 THEN '30-39'
                WHEN MONTHS BETWEEN 40 AND 49 THEN '40-49'
                ELSE '50-'
             END AS MONTHS,
         CUST,
         CATEGORY
    FROM mytable
)
GROUP BY MONTHS