如何(MySQL)乘以列，然后乘以总和行? [英] How to (MySQL) multiply columns and then the sum rows?

问题描述

我有这张桌子:

id    |   payment_id   | quantity  |  unit cost
1           633             1            750  
2           633             1            750 
3           632             2            750 
4           632             2            750 

我需要的是:

payemnt_id  |   total
    633           1500
    632           3000 

您也可以将其视为国家/地区，然后尝试查找每个国家/地区的总数.我确定有一些类似的教程，但STFW找不到.

You can also think of this as Countries and then you are trying to find the total for each Country. I was sure there were some tutorials like this but could not find by STFW.

推荐答案

您只需将公式(表达式)放在SUM中:

You can simply put the formula (expression) inside SUM:

SELECT payment_id, SUM(`unit cost` * quantity) AS total
FROM myTable
GROUP BY payment_id

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