mysql - SQL显示年龄范围

Question

我正在写一个年龄范围的查询，我想在其中显示所有年龄段的人数，例如

    AGE   PEOPLE
   "0-10"  0
   "11-20" 2
   "21-30" 5
   "31-40" 0
   "41-50" 1

我试过

SELECT SUM(CASE WHEN age < 10 THEN 1 ELSE 0 END) AS [Under 10],
        SUM(CASE WHEN age BETWEEN 11 AND 20 THEN 1 ELSE 0 END) AS [11-20],
        SUM(CASE WHEN age BETWEEN 21 AND 30 THEN 1 ELSE 0 END) AS [21-30]
 FROM people

但是它将范围显示为列名

   0-10  11-20 21-30 31-40 41-50
     0     2     5     0    1

这是我不想要的。

我也试过 GROUP BY 但它没有显示计数为 0 的范围。

Answer 1

您可以使用UNION ALL:

SELECT '[Under 10]' as Age, SUM(CASE WHEN age < 10 THEN 1 ELSE 0 END) as People
FROM people
UNION ALL
SELECT '[11-20]', SUM(CASE WHEN age BETWEEN 11 AND 20 THEN 1 ELSE 0 END)
FROM people
UNION ALL
SELECT '[21-30]', SUM(CASE WHEN age BETWEEN 21 AND 30 THEN 1 ELSE 0 END)
FROM people;