On the various grids throughout DonorSnap, use the teeny drop-down arrow next to a field heading to filter Greater than or Equal to, Contains, etc. and many other options.
NULL means that there is no value in the field.
EMPTY means that there is a blank value in the field.
While these two are similar in some respects, they mean different things in databases.
Why do some of my contact have a NULL value and some have an EMPTY value?
This might happen if you add new fields to your database, especially with dropdown fields. When you add a new dropdown field, it can be a good idea to use Excel Import to perform a mass update on all of your contacts to update the value in their record for that field. If you do not do this, some of your contacts might have a NULL value and others have an EMPTY value as time goes on. This isn’t always a problem, but if you are using the IsNull, NotIsNull, IsEmpty, of NotIsEmpty, your results might not be what you expect.
If a contact record existed before a new field was added, there will be a NULL value in that field for all existing contacts. If a new contact record is added after that field is created, it will have an EMPTY value when saved (unless you entered another value). When one of the existing records is opened and saved, that new field will be saved as EMPTY.
IMPORTANT NOTE: Default Values for new fields
When you select a default value as you create a new field, all existing records will still have a NULL value in that field until the record is opened and saved. All new records added after the default value is added will be saved with the default value unless another value is entered. If you need your existing contact records to contain the default value in your new field, you will need to use Excel Import to perform a mass contact update.