mysql - 我可以在 Mysql 中的两列之间求和吗？

Question

我想做的是以下几点：

SELECT SUM(ABS(`number_x` - `number_y`)) AS `total_difference` FROM `table`

表如下：

编号 | number_x | number_y

1 | 4 | 2

2 | 3 | 2

3 | 2 | 4

所以答案应该是：(4 - 2 = 2) + (3 - 2 = 1) + (2 - 4 = 2) = 5

我可以在 MySQL 中执行此操作吗？如何操作？

谢谢！

Answer 1

您发布的查询应该没有问题：

SELECT SUM(ABS(`number_x` - `number_y`)) AS `total_difference` 
FROM `table`

或者，如果您想使用这样的子查询来编写它：

SELECT SUM(diff) AS `total_difference` 
FROM
( 
    SELECT Id, ABS(number_x - number_y) diff
    FROM TableName
) t

Answer 2

SELECT SUM(ABS(`number_x` - `number_y`)) AS `total_difference` FROM `table`

或者你可以用其他方式写，但我只喜欢上面

SELECT ABS(SUM(number_x) - SUM(number_y)) AS total_difference FROM table