MySQL SUM值两列之间的差异

Question

我的一个表中有两列名为TIME_OUT和TIME_IN。这些都是十进制值。我基本上想要总结这些列的差异。我有下面的查询输出差异没有问题，但我想然后总结差异：

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添加到查询中，以便查询显示：

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

这会添加列＆＃39;差异＆＃39;

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