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这是我的数据库表的简化版本。

ID 首次注册 公里
1 2017-03-24 234
2 2019-10-08 3456
3 2020-02-07 2454
4 2019-11-28 7686
5 2019-01-18 4564

该表包含汽车数据，例如：首次注册日期、里程、价格、车型...

我的目标是构建查询以从此数据库表中获取分析指标。我的最终目标应该是这样的：

在此处输入图像描述

我需要使用首次注册日期来构建年龄组，并在此基础上提取其他数据。

目前我已经解决了第一列和第二列。SQL 查询如下所示：

SELECT SUM(CASE WHEN date_part('year', age(firstregistration))<1 THEN 1 ELSE 0 END) AS "0-1",
    SUM(CASE WHEN date_part('year', age(firstregistration)) BETWEEN 1 AND 2 THEN 1 ELSE 0 END) AS "1-2",
    SUM(CASE WHEN date_part('year', age(firstregistration)) BETWEEN 2 AND 3 THEN 1 ELSE 0 END) AS "2-3",
    SUM(CASE WHEN date_part('year', age(firstregistration)) BETWEEN 3 AND 4 THEN 1 ELSE 0 END) AS "3-4",
    SUM(CASE WHEN date_part('year', age(firstregistration)) BETWEEN 4 AND 5 THEN 1 ELSE 0 END) AS "4-5",
    SUM(CASE WHEN date_part('year', age(firstregistration)) BETWEEN 5 AND 6 THEN 1 ELSE 0 END) AS "5-6",
    SUM(CASE WHEN date_part('year', age(firstregistration)) BETWEEN 6 AND 7 THEN 1 ELSE 0 END) AS "6-7",
    SUM(CASE WHEN date_part('year', age(firstregistration)) BETWEEN 7 AND 8 THEN 1 ELSE 0 END) AS "7-8",
    SUM(CASE WHEN date_part('year', age(firstregistration)) BETWEEN 8 AND 9 THEN 1 ELSE 0 END) AS "8-9",
    SUM(CASE WHEN date_part('year', age(firstregistration)) BETWEEN 8 AND 9 THEN 1 ELSE 0 END) AS "9-10",
    SUM(CASE WHEN date_part('year', age(firstregistration)) >= 10 THEN 1 ELSE 0 END) AS ">=10" FROM car_table

为此，我得到如下所示的输出：

在此处输入图像描述

这个结果非常好，它解决了第一张图像上图表的前两列。现在我无法按这些组添加平均公里数据。

有谁知道如何无痛地实现它？需要补充的重要一点是，平均 KM 查询不需要成为我的第一个查询的一部分。将此作为附加查询就足够了。谢谢。

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1 回答 1

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我认为您只需一次查询即可获得结果。


SELECT  age , COUNT(age) as NroCars , AVG(km) , AVG(price) FROM (
     SELECT  date_part('year', age(firstregistration)) as age,
             km ,
             price
     FROM TABLE 
) temp_table
GROUP BY age
于 2021-04-14T16:31:30.367 回答