Abstract
Assume an ORM-diagram where there exist two (or more) paths from one entity type to another through a sequence of many-to-one binary facts. Here we may have a join-equality constraint saying that if we follow the different paths from an instance of the first entity type, we should find the same instance of the second entity type. This constraint is inherent in most ticketing/reservation systems, where it may give rise to overlapping foreign keys in the relational database. Another interesting observation is that if a relation is in 3NF, but not in BCNF, there must be a join-equality constraint in the underlying model.
This is a preview of subscription content, log in via an institution to check access.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
Preview
Unable to display preview. Download preview PDF.
References
Codd, E.F.: Recent investigations in Relational Database Systems. In: Proceedings of the IFIP Congress (1974)
Codd, E.F.: Extending the Database Relational Model to Capture More Meaning. ACM Transactions on Database Systems 4(4) (1979)
Date, C.: Relational Database, Writings. Addison Wesley, Reading (1990)
Elmasri, R., Navathe, S.B.: Fundamentals of Database Systems. Pearson/Addison Wesley, Boston (2007)
Halpin, T.: Join Constraints, http://www.orm.net/pdf/JoinConstraints.pdf
Halpin, T., Morgan, T.: Information Modeling and Relational Databases, 2nd edn. Morgan Kaufmann Publishers, San Francisco (2008)
Skagestein, G.: Data i fokus, Universitetsforlaget, Oslo (1991)
Skagestein, G., Thorvaldsen, A.: Arbeidshefte til Fra virkelighet til datamodell, Universitetsforlaget, Oslo (1987)
Author information
Authors and Affiliations
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 2008 Springer-Verlag Berlin Heidelberg
About this paper
Cite this paper
Skagestein, G., Normann, R. (2008). A Closer Look at the Join-Equality Constraint. In: Meersman, R., Tari, Z., Herrero, P. (eds) On the Move to Meaningful Internet Systems: OTM 2008 Workshops. OTM 2008. Lecture Notes in Computer Science, vol 5333. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-540-88875-8_102
Download citation
DOI: https://doi.org/10.1007/978-3-540-88875-8_102
Publisher Name: Springer, Berlin, Heidelberg
Print ISBN: 978-3-540-88874-1
Online ISBN: 978-3-540-88875-8
eBook Packages: Computer ScienceComputer Science (R0)