Encyclopedia of Database Systems

2018 Edition
| Editors: Ling Liu, M. Tamer Özsu

Normal Form ORA-SS Schema Diagrams

  • Gillian DobbieEmail author
  • Tok Wang Ling
Reference work entry
DOI: https://doi.org/10.1007/978-1-4614-8265-9_5041


NF-SS; Normalizing ORA-SS diagrams


Normal forms have been defined for data models, such as the relational data model, the nested relational data model, the object-oriented data model and more recently, the semi-structured data model, to recognize (and remove) certain kinds of redundant data. A normal form that has been defined for semi-structured data, based on the ORA-SS data model, is described.

Key Points

The definition of a normal form for ORA-SS (Object-Relationship-Attribute data model for Semi-structured data) diagrams is based on the definition of a normal form for the nested relational data model as described by Ling and Yan [1], recognizing the similarity between the nesting relationship in the nested relational data model and hierarchies in the semi-structured data model.

The definition for NF ORA-SS (normal form for the ORA-SS data model) can be broken into three main parts. The first part ensures that every object class is normalized. The second part...

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Recommended Reading

  1. 1.
    Ling TW, Yan LL. NF-NR: a practical normal form for nested relations. J Syst Integr. 4(4):309–40.CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC, part of Springer Nature 2018

Authors and Affiliations

  1. 1.University of AucklandAucklandNew Zealand
  2. 2.National University of SingaporeSingaporeSingapore