Extending the Relational Database Model to Support Goal Queries.
Amihai Motro · 1986
Requests for data can be classified roughly into two kinds: specific requests and goals. A specific request establishes a rigid qualification, and is concerned only with data that matches it precisely. A goal, on the other hand, establishes a target qualification and is concerned with data which is close to this target. Many database queries are in effect goals, but because database management systems lack the mechanisms to handle goals, they must be emulated with specific requests. Usually, this means the user is forced to retry a particular query repeatedly with minor modifications, until it matches something satisfactory. In this paper we show how to handle goals directly, in the environment of relational databases. We define the concept of distance between data values that are from the same domain and show how to incorporate it into relational systems. Based on this distance, we define three types of goals: neighborhood goals, optimum goals and priority goals. We then demonstrate how a typical query language can be extended to express goals, and give guidelines for implementation. Eqxn Lklobare System: krny Kersdiberg, Editor. Copyright I987 by The Benjamin/Cummings Publishing Gmpny, Inc, 130 EXPERT DATABASE SYSTEMS