MySQL SUM 两列之间差异的值

Question

我的一个表中有两列，分别称为 TIME_OUT 和 TIME_IN。这些都是十进制值。我基本上想总结这些列的差异。我有下面的查询可以毫无问题地输出差异，但我想对差异求和：

SELECT (TIME_IN-TIME_OUT) AS DIFF FROM TABLE_timelogs WHERE YEAR(LOG_DATE) = YEAR(NOW());

+------+
| DIFF | 
+------+
| 10.0 |
|  4.0 |
|  3.0 |
+------+

有没有办法将 SUM 集成到查询中，以便最终输出为 17.0？提前谢谢！

Answer 1

将 SUM 添加到您的查询中，以便查询显示为：

SELECT SUM(TIME_IN-TIME_OUT) AS DIFF 
FROM TABLE_timelogs 
WHERE YEAR(LOG_DATE) = YEAR(NOW());

这会添加“diff”列的内容。