FMP Version: All Current Versions Of FileMaker
This function checks to see if a specified field is empty or not. If the field is empty, it returns a TRUE. This function is usually used inside of another logical function like Case or IF. For example, you might have a calculation that checks to see if someone has ever donated money to your cause. If the sum of their donations is empty and they are in your contact database, they are a friend. If they have donated money, they are a donor.
Case( IsEmpty(SumDonations), “Friend”, “Donor”)
FYI... FLIPPING THE RESULT WITH THE NOT OPERATOR
The NOT operator is designed to reverse the truth about a statement. This is kind of like two surfers talking "You were awesome dude, NOT!" It's the same thing with this function, you are giving a statement and then declaring it the opposite of it's intent. If you are giving a true statement, the NOT reverses it to false. If you are giving a false statement, the NOT reverses it to true.
NOT 1=1 ... returns a FALSE
NOT 1=3 ... returns a TRUE
So bringing it back to the IsEmpty function, lets take a look at this statement.
NOT IsEmpty(Date Completed)
Without the NOT operator, if the Date Completed field is empty, it returns a TRUE result. If there is data within the field it returns a FALSE.
With the NOT operator, if the Date Completed field is empty, it returns a FALSE result. If there is data within the field it returns a TRUE.