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作为我从我的问题中得到的答案，这让我因为某种原因而疯狂地申请我的代码，为什么它不起作用。

这是我在表格上的一部分数据。

在此处输入图像描述

原始代码：

SELECT AGE_RANGE, COUNT(*) FROM (
    SELECT CASE
        WHEN YearsOld BETWEEN 0 AND 5 THEN '0-5'
        WHEN YearsOld BETWEEN 6 AND 10 THEN '6-10'
        WHEN YearsOld BETWEEN 11 AND 15 THEN '11-15'
        WHEN YearsOld BETWEEN 16 AND 20 THEN '16-20'
        WHEN YearsOld BETWEEN 21 AND 30 THEN '21-30'
        WHEN YearsOld BETWEEN 31 AND 40 THEN '31-40'
        WHEN YearsOld > 40 THEN '40+'
        END AS 'AGE_RANGE'
        FROM (
            SELECT YEAR(CURDATE())-YEAR(DATE(birthdate)) 'YearsOld' 
            FROM MyTable
        ) B
) A
GROUP BY AGE_RANGE

这是结果。

在此处输入图像描述

我正在尝试做的是，我正在尝试添加另一列，该列将计算该区域中有多少人，正如您在顶部图片中看到的那样，包括珀斯、西澳大利亚、森伯里，维多利亚等。

第一次尝试解决我的问题

正如您将在下面看到的，我添加了位置，并添加了 COUNT(location) loc 来获取位置的名称并计算表中重复的位置数量。

SELECT AGE_RANGE, COUNT(*), location, COUNT(location) loc FROM (
    SELECT CASE
        WHEN YearsOld BETWEEN 0 AND 5 THEN '0-5'
        WHEN YearsOld BETWEEN 6 AND 10 THEN '6-10'
        WHEN YearsOld BETWEEN 11 AND 15 THEN '11-15'
        WHEN YearsOld BETWEEN 16 AND 20 THEN '16-20'
        WHEN YearsOld BETWEEN 21 AND 30 THEN '21-30'
        WHEN YearsOld BETWEEN 31 AND 40 THEN '31-40'
        WHEN YearsOld > 40 THEN '40+'
        END AS 'AGE_RANGE', 'location'
        FROM (
            SELECT YEAR(CURDATE())-YEAR(DATE(birthday)) 'YearsOld' 
            FROM event_participants
        ) B
) A
FROM event_participants WHERE location <> '' GROUP BY location HAVING loc >= 1 ORDER BY loc DESC LIMIT 5

结果到..

在此处输入图像描述

显然，听从上帝的帮助并不好。

我第二次尝试解决这个问题

SELECT AGE_RANGE, COUNT(*), location FROM (
    SELECT CASE
        WHEN YearsOld BETWEEN 0 AND 5 THEN '0-5'
        WHEN YearsOld BETWEEN 6 AND 10 THEN '6-10'
        WHEN YearsOld BETWEEN 11 AND 15 THEN '11-15'
        WHEN YearsOld BETWEEN 16 AND 20 THEN '16-20'
        WHEN YearsOld BETWEEN 21 AND 30 THEN '21-30'
        WHEN YearsOld BETWEEN 31 AND 40 THEN '31-40'
        WHEN YearsOld > 40 THEN '40+'
        END AS 'AGE_RANGE', 'location'
        FROM (
            SELECT YEAR(CURDATE())-YEAR(DATE(birthday)) 'YearsOld' 
            FROM event_participants
        ) B
) A
GROUP BY AGE_RANGE

结果是……

在此处输入图像描述

它不显示国家/地区的名称，而仅显示位置。

出色地..

长话短说，代码有什么问题？这东西有什么解决办法吗？

就像，我想要的结果是，

AGE_RANGE COUNT(*) location            total number of same location

16-20        4     Name of location                 #

21-30       45     Name of location                 #

31-40       79     Name of location                 #

40+        102     Name of location                 #
4

3 回答 3

1

这应该可行：将每个子查询视为它自己的表，因此您只需要确保选择您需要的所有列。(CASE WHEN THEN END AS) 实际上只是一个单列值。您可能还希望按位置分组，以便为​​不同的位置获得相同的年龄范围。（例如加拿大的 11-15 和美国的 11-15）

SELECT AGE_RANGE, COUNT(*), A.location FROM (
        SELECT CASE
            WHEN YearsOld BETWEEN 0 AND 5 THEN '0-5'
            WHEN YearsOld BETWEEN 6 AND 10 THEN '6-10'
            WHEN YearsOld BETWEEN 11 AND 15 THEN '11-15'
            WHEN YearsOld BETWEEN 16 AND 20 THEN '16-20'
            WHEN YearsOld BETWEEN 21 AND 30 THEN '21-30'
            WHEN YearsOld BETWEEN 31 AND 40 THEN '31-40'
            WHEN YearsOld > 40 THEN '40+'
            END AS 'AGE_RANGE', B.location
            FROM (
                SELECT YEAR(CURDATE())-YEAR(DATE(birthday)) 'YearsOld',
                location /* << just missing this select */
                FROM event_participants
            ) B
    ) A
    GROUP BY A.location, AGE_RANGE
于 2013-06-27T05:43:41.083 回答
1

尝试这个

SELECT AGE_RANGE, COUNT(*), location FROM (
        SELECT CASE
            WHEN YearsOld BETWEEN 0 AND 5 THEN '0-5'
            WHEN YearsOld BETWEEN 6 AND 10 THEN '6-10'
            WHEN YearsOld BETWEEN 11 AND 15 THEN '11-15'
            WHEN YearsOld BETWEEN 16 AND 20 THEN '16-20'
            WHEN YearsOld BETWEEN 21 AND 30 THEN '21-30'
            WHEN YearsOld BETWEEN 31 AND 40 THEN '31-40'
            WHEN YearsOld > 40 THEN '40+'
            END AS 'AGE_RANGE', 'location'
            FROM (
                SELECT YEAR(CURDATE())-YEAR(DATE(birthday)) 'YearsOld'
                FROM event_participants
            ) B
    ) A
    GROUP BY location, AGE_RANGE
于 2013-06-27T05:54:54.373 回答
0

这是不正确的：-

SELECT AGE_RANGE, COUNT(*), location FROM

当你GROUP BY在 select 中使用属性列表时，必须要么应用于聚合函数，要么必须是GROUP BY子句的一部分。

在下面的示例中，您无法显示该位置的名称，因为其中的人age-group可能属于不同的位置：-

AGE_RANGE COUNT(*) location            total number of same location

16-20        4     Name of location                 #

21-30       45     Name of location                 #
于 2013-06-27T05:45:59.417 回答