Question

I have several tables that contain several strings for fields. Some of these fields may or may not always contain data. If I create a record with a string field that’s null at the time of the record’s creation, does it become a problem when I do a read query of that record because the field is null or does the query return an empty string?
What’s considered based? Non-nullabe strings or nullable strings, and when to know the difference?

Thanks for your suggestions.

Answer 1

The query will return an empty string if that is what is stored in the database and a null value (System.DBNull) if it is a nullable string with a null in it.

The decision, however, should be based on the data you are modeling, not the functionality of queries.

Null in a DB generally means that a value is either unknown or was left blank. This can be distinct from an empty string which could be used to mean there IS no value.

Take for example a MiddleName field. You might want to distinguish between someone with no middle name (empty string) and someone who didn’t enter it yet (Null). In this case you’d want a nullable string field.