The Early Days: Visual Query Systems

Abstract

Some of the earliest efforts to provide a user-centered approach to database management were the introduction of Visual Query Languages (VQLs). VQLs are languages for querying databases that use a visual representation to depict the domain of interest and express related requests. VQLs provide a language to express the queries in a visual format, and they are oriented towards a wide spectrum of users, especially novices who have limited computer expertise and who generally ignore the inner structure of the accessed database. Systems implementing VQLs are usually called Visual Query Systems (VQSs) (Catarci et al., 1997). In VQSs, the data representation language provides the user with a more natural view of the information, thus shortening the interpretation path that the user must perform to recognize the reality of interest from its computer-oriented representation. The same is true for the activity of expressing a query where direct manipulation of icons or navigation in diagrams substitute names of commands. Furthermore, visual languages are more flexible than traditional languages, where usually the learning of formal statements is needed to express even simple queries, each query being stated by a linear string where both operators and operands are expressed by words.