If you want to know how many days have elapsed from some date that is in
a date field of an Access database (for example how may days ago did
someon sign up), you can easiliy make a query that will provide that
for every entry in the database).
All you have to do in the query builder is type in the expression:
DaysSinceSignup: Date()-[signupdate]
where in this example the query field name is DaysSinceSignup and the
sinupdate is the field from which you are counting the dates.
Of course you need to have brought the appropriate fields from your
table into the query.