Encyclopedia of Database Systems

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

Semi-structured Query Languages

  • Dan Suciu
Reference work entry
DOI: https://doi.org/10.1007/978-1-4614-8265-9_339

Definition

A query language for semi-structured data allows a user to extract items from a semi-structured data instance, or to transform it into another semi-structured data instance. The first type of expressions are called queries, the latter kind of expressions are interchangeably called queries or transformations. Query languages can be classified along several dimensions:
  1. 1.

    Expressive power. What kind of queries or transformations can they express?

     
  2. 2.

    Querying vs. restructuring. Some query languages allow only the extraction of items from the data, others allow the data to be transformed.

     
  3. 3.

    Compositionality. Can the output of a query be used as input in another query expressed in the language, and is the composed transformation still expressible in the same language? Query languages that are restricted to extraction only are not compositional, because the type of their outputs are not semi-structured data instances. Transformation languages may fail to be compositional if...

This is a preview of subscription content, log in to check access.

Recommended Reading

  1. 1.
    Abiteboul S, Quass D, McHugh J, Widom J, Wiener J. The Lorel query language for semistructured data. 1996. http://www-db.stanford.edu/lore/.
  2. 2.
    Buneman P, Davidson S, Suciu D. Programming constructs for unstructured data. In: Proceedings of the Workshop on Database Programming Languages; 1995.Google Scholar
  3. 3.
    Deutsch A, Fernandez M, Florescu D, Levy A., Suciu D. A query language for XML. In: Proceedings of the 8th International World Wide Web Conference; 1999. p. 77–91.CrossRefGoogle Scholar
  4. 4.
    Fernandez M, Florescu D, Kang J, Levy A, Suciu D. Catching the boat with Strudel: experience with a Web-site management system. In: Proceedings of the ACM SIGMOD International Conference on Management of Data; 1998. p. 414–25.Google Scholar
  5. 5.
    Papakonstantinou Y, Abiteboul S, Garcia-Molina H. Object fusion in mediator systems. In: Proceedings of the 22th International Conference on Very Large Data Bases; 1996. p. 413–24.Google Scholar

Copyright information

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

Authors and Affiliations

  1. 1.University of WashingtonSeattleUSA

Section editors and affiliations

  • Frank Tompa
    • 1
  1. 1.David R. Cheriton School of Computer ScienceUniv. of WaterlooWaterlooCanada