PHP计数具有相同ID的值 [英] PHP count values with same id

问题描述

我当前的项目:我正在尝试创建一个公司所有汽车的概览.

My current project: I'm trying to create an overview of all cars in a company.

我得到以下mysql结果表:

I get the following mysql result table:

|car_id|distance|
|   1  |  33875 |
|   1  |  33027 |
|   1  |  31579 |
|   2  | 125636 |
|   2  | 124937 |

距离"是加满油后的里程数.

The "Distance" is the mileage after a fill up.

我需要什么?

我需要每辆车的总距离.

I need the total distance for each car.

结果应该是这样的:

|car_id|distance|
|   1  |  2296  | (33875 - 31579)
|   2  |   699  | (125636 - 124937)

推荐答案

您可以使用 group by 子句轻松完成，例如:

You can easily do it with group by clause, e.g.:

SELECT id, (MAX(distance) - MIN(distance)) AS mileage
FROM cars
GROUP BY id;

这是 SQL Fiddle.

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