Encyclopedia of Database Systems

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

Current Semantics

  • Michael H. Böhlen
  • Christian S. Jensen
  • Richard T. Snodgrass
Reference work entry
DOI: https://doi.org/10.1007/978-1-4614-8265-9_1068

Synonyms

Temporal upward compatibility

Definition

Current semantics constrains the semantics of non-temporal statements applied to temporal databases. Specifically, current semantics requires that non-temporal statements behave as if applied to the non-temporal database that is the result of taking the timeslice of the temporal database at the current time.

Main Text

Current semantics [5] requires that queries and views on a temporal database consider the current information only and work exactly as if applied to a non-temporal database. For example, a query to determine who manages the high-salaried employees should consider the current database state only. Constraints and assertions also work exactly as before: they are applied to the current state and checked on database modification.

Database modifications are subject to the same constraint as queries: they should work exactly as if applied to a non-temporal database. Database modifications, however, also have to take into...

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References

  1. 1.
    Bair J, Böhlen MH, Jensen CS, Snodgrass RT. Notions of upward compatibility of temporal query languages. Wirtschaftsinformatik. 1997;39(1):25–34.Google Scholar
  2. 2.
    Clifford J, Dyreson C, Isakowitz T, Jensen CS, Snodgrass RT. On the semantics of “NOW” in databases. ACM Trans Database Syst. 1997;22(2):171–214.CrossRefGoogle Scholar
  3. 3.
    Kulkari K, Michels JE. Temporal features in SQL:2011. ACM SIGMOD Rec. 2012;41(3): 34–43.CrossRefGoogle Scholar
  4. 4.
    Melton J, editor. ISO/IEC 9075, database language SQL:2011 Part 2: SQL/foundation, Dec 2011.Google Scholar
  5. 5.
    Snodgrass RT. Developing time-oriented database applications in SQL. San Francisco: Morgan Kaufmann; 1999.Google Scholar

Copyright information

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

Authors and Affiliations

  • Michael H. Böhlen
    • 1
    • 2
  • Christian S. Jensen
    • 3
  • Richard T. Snodgrass
    • 4
    • 5
  1. 1.Free University of Bozen-BolzanoBozen-BolzanoItaly
  2. 2.University of ZurichZürichSwitzerland
  3. 3.Department of Computer Science, Aalborg UniversityAalborgDenmark
  4. 4.Department of Computer Science, University of ArizonaTucsonUSA
  5. 5.Dataware VenturesTucsonUSA