I am working with a Microsoft Access Database helping a non profit
organization try to figure out how many nights in a month people are staying
in there shelter.  I have two fields a Check In Date and Check Out Date
Field.  Therefore to figure out the nights a person stayed, I minus the Check
Out by the Check In Date.  

The problem is if they check in the prior month, let’s say February and
checked out in March, How I can I calculate just the days in March.  The
other problem is if they checked in March and have not checked out yet (null
field), how do I calculate the number of days in March.  This is time
sensitive any assistance anyone can give is greatly appreciated.