SQL：总结DATEDIFFs

Question

使用mysql

2个日期：start_date和end_date。

改变后 TIMEDIFF(start_date, end_date) AS time_diff

我想SUM（）所有time_diff所以我试试这个 SUM(TIMEDIFF(start_date, end_date)) AS time_diff

这回归了我不期望的东西 我做错了什么？

修改 SEC_TO_TIME(SUM(TIME_TO_SEC(TIMEDIFF(end_date, START_DATE)))) AS time_diff

完美无缺

Answer 1

end_date应该是第一个而start_date秒，否则你会得到负值作为输出：

SUM(TIME_DIFF(CAST(end_date AS DATETIME), CAST(start_date AS DATETIME))) AS time_diff

Answer 2

SEC_TO_TIME(SUM(TIME_TO_SEC(TIMEDIFF(end_date, START_DATE)))) AS time_diff