access-database-training - Integrity constraint violated - parent key not found

Access tip:

Calculating The Difference Between Dates

If you wish to calculate the time between two date fields, this can be done in a number of ways:

1. As a calculated field in a query
2. As a calculated control in a form or report
3. As a calculation in a VBA procedure.

The basic syntax to get the number of days between two dates is:

=[One Date Field] - [Another Date Field]

You can also use one of the following functions:

=Month([One Date Field] - [Another Date Field])
which calculates the number of months between the two fields

=Year([One Date Field] - [Another Date Field])
which calculates the number of years between the two fields.

Another function is the DateDiff() function.

It uses an argument to determine how the time interval is measured. For example:

=DateDiff("q",[One Date Field] - [Another Date Field])
returns the number of quarters between the two fields.

Other intervals that can be used in this expression are as follows:
"yyyy" - Years
"m" - Months
"d" - Days
"w" - Weekdays
"ww" - Weeks
"h" - Hours
"n" - Minutes
"s" - Seconds

View all Access hints and tips