Calculate duration between two dates

[Tommy1005]

How would I make a query that does the following:

Updates Column: "Duration from Start to RTT" in my table called SE_Report.

The query updates the column with the number of days it has been since the date in the "Request Letter Sent Date" column and the "Trading Relationship Accepted" column. If there is no date in the "Trading Relationship Accepted" column then it just uses todays date.

Examples:
Request Letter Sent Date: 5/4/2012
Trading Relationship Accepted Date: 5/9/2012
So the column Duration from Start to RTT would have "5"

Another is
Request Letter Sent Date: 5/22/2012
But there is no Trading Relationship Accepted Date so it uses todays date 7/1/2012
So the column Duration from Start to RTT would have "39"

Can anyone help me figure this out?


Here is the Access file with my table.
query.zip

[RuralGuy]

Have you looked at DateDiff() yet?

[Tommy1005]

Yes I'm still a newbie at sql though I only know select statements. Would this require a insert into statement?

[RuralGuy]

I think this link should be helpful for you: http://allenbrowne.com/casu-14.html