A database query language for operations on historical data

  • Rubik Sadeghi

    Student thesis: Doctoral Thesis


    Information in most existing database management systems reflects only the current state of the data. However, many real world applications require the storage of and access to historical information. In this thesis a historical model is presented which integrates comprehensive time processing capabilities into the relational model. The role of time in this model is examined, as is the effect of time on relational algebra. An algebra for historical relations is defined.

    Finally the Historical Query Language (HQL) is defined and implemented. HQL is designed to allow users to interrogate the historical database in a natural way without referring to the time domain explicitly. HQL has a user friendly syntax and supports user-defined functions and recursion.
    Date of AwardDec 1987
    Original languageEnglish

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