Missing information (applicable and inapplicable) in relational databases
- 1 December 1986
- journal article
- Published by Association for Computing Machinery (ACM) in ACM SIGMOD Record
- Vol. 15 (4) , 53
- https://doi.org/10.1145/16301.16303
Abstract
There has been some technical and justified criticism of the treatment of missing information in the data sublanguage SQL and in IBM's Database 2 system (a relational database management system). Some of this criticism has been directed (by mistake) at the relational model. The purpose of this paper is to clarify and extend the treatment of missing information by the relational model. The clarification places heavy emphasis on the semantic aspects of missing information. The extension, which is relatively minor, provides a systematic approach (independent of data type) to dealing with the inapplicability of certain properties to some objects. This extension does not invalidate any part of the present version of the relational model.Keywords
This publication has 6 references indexed in Scilit:
- Inclusion dependencies and their interaction with functional dependenciesJournal of Computer and System Sciences, 1984
- Relational databaseCommunications of the ACM, 1982
- Extending the database relational model to capture more meaningACM Transactions on Database Systems, 1979
- Null values in data base management a denotational semantics approachPublished by Association for Computing Machinery (ACM) ,1979
- A complete axiomatization for functional and multivalued dependencies in database relationsPublished by Association for Computing Machinery (ACM) ,1977
- A relational model of data for large shared data banksCommunications of the ACM, 1970