Question

假设下表：

id    value
-----------
1      3
2      5
3      15
4      18
5      19
6      30

我希望分类并计入几个小组：

group    amount
---------------
'1-5'      2
'6-10'     0
'11-20'    3
'21-50'    1

如何在一个查询中执行此操作？

Answer 1

最简单的方法是在以下情况下将组写入案例：

SELECT grp, count(*)
FROM
(
 SELECT
  CASE
    WHEN value BETWEEN 1 AND 5 THEN '1-5'
    WHEN value BETWEEN 6 AND 10 THEN '6-10'
    ...and so on...
    ELSE '21-50' 
  END as grp
 FROM
  sourcetable
)a
GROUP BY grp

基本上，您根据它们所处的范围将值从一种形式转换为另一种形式，然后计算转换后的值。注意，我已经在21-50范围内使用了ELSE，假设价值从未超过50，如果确实如此，则需要改变范围，否则技术上，100将在＆＃34; 21下提交。 -50＆＃34;还

Answer 2

另一种方法是使用生成的范围表：

;WITH CTE_Groups AS (
    SELECT 1 AS min, 5 AS max, '1-5' AS grp
    UNION ALL
    SELECT 6 AS min, 10 AS max, '6-10' AS grp
    UNION ALL
    SELECT 11 AS min, 20 AS max, '11-20' AS grp
    UNION ALL
    SELECT 21 AS min, 50 AS max, '21-50' AS grp
)
SELECT
    G.grp,
    COUNT(T.id) AS amount
FROM
    CTE_Groups G
LEFT OUTER JOIN My_Table T ON T.value BETWEEN G.min AND G.max
GROUP BY
    G.grp, G.min
ORDER BY
    G.min

将数字汇总到类中

2 个答案: