[英]How to store Derived Column in MySQL
I have a table A which have Start_time and End_time as columns, i am calculating the difference of these two columns as我有一个表 A ,其中有Start_time和End_time作为列,我正在计算这两列的差异
Select timediff(End_time, Start_time) as TF from A
Now i want to sum of all time periods present ln TF column.现在我想对 ln TF列中存在的所有时间段求和。
I searched alot but could not found anything related to it我搜索了很多,但找不到任何与之相关的内容
Timediff()
will give you result in HH:MM:SS
format. Timediff()
将为您提供HH:MM:SS
格式的结果。 In order to SUM()
them up, you need to first convert them into numbers (in this case, seconds);为了将它们SUM()
起来,您需要先将它们转换为数字(在本例中为秒); add them up using SUM()
;使用SUM()
将它们相加; and then convert them back to HH:MM:SS
format:然后将它们转换回HH:MM:SS
格式:
SELECT SEC_TO_TIME( SUM( TIME_TO_SEC( TIMEDIFF(End_time, Start_time) ) ) )
FROM A
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