Encyclopedia of Database Systems

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

Object Relationship Attribute Data Model for Semistructured Data

  • Gillian DobbieEmail author
  • Tok Wang Ling
Reference work entry
DOI: https://doi.org/10.1007/978-1-4614-8265-9_5042


ORA-SS data model; ORA-SS schema diagram


When a database schema is designed, a data model is initially used to model the real world constraints that are taken into account in the design of the schema. For semi-structured database design, it is necessary to capture the following constraints: object classes, n-ary relationship types, attributes of object classes, attributes of relationship types, cardinality, participation and uniqueness constraints, ordering, irregular and heterogeneous structures, for both data- and document-centric data.

Key Points

The ORA-SS (Object-Relationship-Attribute Data Model for Semi-structured Data) data model was designed [1] specifically to capture the constraints that are necessary for designing semi-structured databases, for normalization of schemas, and for defining views.

Figure 1models the scenario where there is a department, with a name and many courses. A course has a unique code, a title, and many students, and a student has...
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Recommended Reading

  1. 1.
    Ling TW, Lee ML, Dobbie G. Semi-structured database design. Berlin/Heidelberg/New York: Springer; 2005.zbMATHGoogle 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