Access subtract time | 易学教程

问题

How can I subtract two times in an Access table?

query must do it automatically. I need to subtract left time with arrived, so then I get hours of working employed:

Query must fill hours column in table, so I can get it in c# program.

[Left]- [Arrived]

回答1:

In access, if the fields are date/time type, it is as simple as substract them and format output as desired. The substraction results in days and fraction of days. If you want it in hours, just multiply by 24, which gives you, hours and fracition of hours

SELECT cdbl([Left] - [Arrived]) * 24 as worked_hours FROM yourtable

回答2:

DateDiff

DateDiff ( interval, date1, date2, [firstdayofweek], [firstweekofyear])

http://www.techonthenet.com/access/functions/date/datediff.php

DateDiff ("h", [Arrived], [Left])

回答3:

As Russell mentioned, use DateDiff function. I tested on a test MsAccess DB and it works. Here is my select statement:

SELECT DateDiff('n',[Arrived],[Left])/60 AS Worked, 
       DateDiff('s',[Arrived],[Left])/3600 AS Worked2, 
       *
FROM Table1;

Sample Results:

Worked               Worked2               Left                  Arrived
1                    0.999722222222222      4/9/2013 3:00:00 PM  4/9/2013 2:00:01 PM
0.833333333333333    0.833055555555556      4/9/2013 3:00:00 PM  4/9/2013 2:10:01 PM
1.66666666666667E-02 2.77777777777778E-04   4/9/2013 3:00:00 PM  4/9/2013 2:59:59 PM
24                   23.9997222222222       4/9/2013 3:00:00 PM  4/8/2013 3:00:01 PM

As you can see, the Worked2 approach (by second) is a bit more accurate.

来源：https://stackoverflow.com/questions/15910341/access-subtract-time

标签

sql

ms-access

datetime

ms-access-2007