Missing values and NULL mark problems in relational databases

Abstract

The relational approach of database management has developed a lot since its creation and also the SQL language. In spite of the fact that Codd the founding father of relational database management did a huge and nearly perfect job even without antecedents, there are some problematic points in SQL standard(s) and/or RDBMS software(s), such as the possibilities of dealing with missing values. Codd (1990) in his original book argues in favor of the necessity of introducing the I and A marks instead of the NULL mark. In this paper I’m investigating from the point of view of both theory and practice whether or not the only NULL mark is proper and enough for its purpose.

The relational approach of database management has developed a lot since its creation and also the SQL language. In spite of the fact that Codd the founding father of relational database management did a huge and nearly perfect job even without antecedents, there are some problematic points in SQL standard(s) and/or RDBMS software(s), such as the possibilities of dealing with missing values. Codd (1990) in his original book argues in favor of the necessity of introducing the I and A marks instead of the NULL mark. In this paper I’m investigating from the point of view of both theory and practice whether or not the only NULL mark is proper and enough for its purpose.