mysql - ELSE '60+' 在 CASE 语句中不起作用，但 ELSE 'Others' 起作用

Question

这是我用来查找给定年龄范围内有多少人的 SQL 语句（以百分比为单位）。

SELECT
CASE 
WHEN FLOOR(DATEDIFF(NOW(), adherent_naissance)/365.4) <= 10 THEN '-10' 
WHEN FLOOR(DATEDIFF(NOW(), adherent_naissance)/365.4) <= 20 THEN '11-20'
    WHEN FLOOR(DATEDIFF(NOW(), adherent_naissance)/365.4) <= 30 THEN '21-30'
    WHEN FLOOR(DATEDIFF(NOW(), adherent_naissance)/365.4) <= 60 THEN '31-60'
ELSE '60+' 
END AS Age, 
(Count(adherent_naissance)* 100 / (Select Count(*) From adherent)) as Pourcentage
FROM adherent
GROUP BY 
CASE 
WHEN Age <= 10 THEN '-10' 
WHEN Age <= 20 THEN '11-20'
    WHEN Age <= 30 THEN '21-30'
    WHEN Age <= 60 THEN '31-60'
ELSE '60+' 
END

一切正常，除非有人属于“其他”类别，然后我有一个奇怪的行为：该人被计入前一个类别。

也就是说我得到了：

Age     Pourcentage
11-20   33.3333
21-30   33.3333
31-60   33.3333

代替 ：

Age     Pourcentage
11-20   33.3333
21-30   33.3333
31-60   16.6667
60+     16.6667

ELSE '60'也不起作用，但ELSE 'Others'确实有效......

任何的想法 ？谢谢 ！

注意（测试数据）：SELECT adherent_naissance FROM adherent WHERE 1返回

adherent_naissance
1991-01-09
1990-03-28
1995-09-10
1964-01-10
1992-08-19
1920-02-21

如果有帮助，我正在使用 MySQL 5.5.24-log。

Answer 1

您需要将相同的 CASE 表达式添加到 GROUP BY 子句中

SELECT
CASE 
WHEN FLOOR(DATEDIFF(NOW(), adherent_naissance)/365.4) <= 10 THEN '-10' 
WHEN FLOOR(DATEDIFF(NOW(), adherent_naissance)/365.4) <= 20 THEN '11-20'
    WHEN FLOOR(DATEDIFF(NOW(), adherent_naissance)/365.4) <= 30 THEN '21-30'
    WHEN FLOOR(DATEDIFF(NOW(), adherent_naissance)/365.4) <= 60 THEN '31-60'
ELSE '60+' 
END AS Age, 
(Count(adherent_naissance)* 100 / (Select Count(*) From adherent)) as Pourcentage
FROM adherent
GROUP BY 
CASE 
WHEN FLOOR(DATEDIFF(NOW(), adherent_naissance)/365.4) <= 10 THEN '-10' 
WHEN FLOOR(DATEDIFF(NOW(), adherent_naissance)/365.4) <= 20 THEN '11-20'
    WHEN FLOOR(DATEDIFF(NOW(), adherent_naissance)/365.4) <= 30 THEN '21-30'
    WHEN FLOOR(DATEDIFF(NOW(), adherent_naissance)/365.4) <= 60 THEN '31-60'
ELSE '60+' 
END

SQLFiddle上的演示