Should Nulls be considered harmful?

An Issue Paper by FFE Software, Inc.

Recently, the use of Nulls in relational database has been called into question by C. J. Date and other writers. They have suggested various schemes for using default values as a replacement for Null processing in relational database.

This paper examines these issues in detail, presenting both sides of the controversy. Are Nulls a problem similar to Dykstra's 'Goto's considered harmful.', or are they an effective, useful technique for dealing with missing information? There are many, including E. F. Codd, the father of relational database, who believe Nulls are the right solution for databases.

Contents:

• Missing Information Exists!, an overview of missing information, its representation in database and effects on database processing.
• How Relational solves the Missing Information Problem, a description of the Relational Database Model's solution for missing information - Nulls.
• The Controversy over Nulls, a discussion of the arguments for and against Nulls.
• Schemes for Default Values, an examination of various proposed schemes for using Default Values, comparing them to Null processing.
• Conclusion, an answer to the question - Should Nulls be considered harmful?
• References, references to printed books and articles, not available on the Internet.

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