The implementation of the visual query language CQL for transitive and
relational computation
Järvelin, K. (1) & Niemi, T. (2) & Salminen, A. (3)
(1) Department of Information Studies
(2) Department of Computer and Information Sciences
University of Tampere
FIN-33014 UNIVERSITY OF TAMPERE, Finland
(3) Dept. of Computer Science and Information Systems
University of Jyväskylä, P.O.Box 35
FIN-40351 JYVÄSKYLÄ, Finland
REFERENCE:
Järvelin, K. & Niemi, T. & Salminen, A. (2000). The implementation of the visual query
language CQL for transitive and relational computation. Data & Knowledge Engineeging, 31(), to appear.
Abstract
CQL (Classification Query Language) is a high-level visual query language with a great expressive power.
In CQL the processing of ordinary relations and classifications based on transitive relationships is
integrated seamlessly. Relations and classifications are represented in the visual interface in a
uniform way through relation and classification skeletons. All query formulation in CQL is
QBE-like — based on the intuitive way of filling constants and sample values into the skeletons.
In order to guarantee great expressive power, relational and classification expressions can be
nested freely with each other at unlimited nesting levels. Recursive definition of transitive
processing is totally hidden from the users. The query interface and its implementation are
described briefly.
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