Extensions to SQL for Historical Databases

  • Authors:
  • N. L. Sarda

  • Affiliations:
  • -

  • Venue:
  • IEEE Transactions on Knowledge and Data Engineering
  • Year:
  • 1990

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Abstract

A historical management system (HDBMS) is described which uses an extended relational data model with state-oriented, instead of 'cubic', conceptualization. Two types of historical relations, called state and event relations, are provided for modeling real-world objects. The query language SQL has been extended for definition, retrieval, and update of historical relations. The extended SQL, called HSQL, is a superset of SQL. The author defines a few primitive algebra operations for historical relations, and uses them as a basis for extensions to SQL. In this way, HSQL retains the elegant structural and algebraic framework of SQL. HSQL contains a few new clauses, many operations and built-in functions on time domain, and facilities for retrospective updates and time-rollback.