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A temporal query language for a conceptual model

  • Ramez Elmasri
  • Vram Kouramajian
Chapter
Part of the Lecture Notes in Computer Science book series (LNCS, volume 759)

Abstract

This chapter was a summary of our work in temporal conceptual models and query languages [173, 178, 174, 179], Our model distinguishes between conceptual and temporal objects, and characterizes the properties of entities (conceptual objects), entity roles (temporal objects), and (temporal and non-temporal) attributes. It also defines temporal constraints among entity roles, differentiates between temporal and conceptual relationships, and provides rules for preserving temporal integrity constraints.

The query language is a temporal extension of GORDAS [177, 176, 178], The temporal query language derives its power from the distinction between temporal and conceptual objects/relationships. It provides natural and high level temporal element constructor operators that simplify temporal query expressions. These operators utilize the entity existence times and the role lifespans in query formulations, without having to refer explicitly to time values. They also use the concepts of boolean conditions, true-times, and temporal projections [178].

Our query language allows temporal element constructor operators to be defined over entities, entity roles and temporal attributes. It supports temporal version restriction operators and allows multiple temporal scopes in a temporal projection. In addition, the concept of CONTINUOUS and DISCONTINUED temporal elements can be used to specify conditions such as ALWAYS and SOMETIME from temporal logic.

Keywords

Query Language Entity Type Existence Time Conceptual Object Temporal Element 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer-Verlag Berlin Heidelberg 1993

Authors and Affiliations

  • Ramez Elmasri
    • 1
  • Vram Kouramajian
    • 1
  1. 1.Computer Science Engineering DepartmentThe University of Texas at ArlingtonArlingtonUSA

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