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We present a visual language for querying and transforming XML data. The language is based on a visual document metaphor and the notion of document patterns and rules. It combines a dynamic form-based interface for defining queries and transformation rules with powerful pattern matching capabilities and offers thus a highly expressive visual language. The design of the visual language is specifically targeted at end users.

The visual object query language (VOQL) recently proposed for object databases has been successful in visualizing path expressions and set-related conditions, and providing formal semantics. However, VOQL has several problems. Due to unrealistic assumptions, only set-related conditions can be represented in VOQL. Due to lack of the explicit language construct for the notion of variables, queries are often awkward and less intuitive. In this paper, we propose VOQL*, which extends VOQL to remove these drawbacks. We introduce the notion of visual variables and refine the syntax and semantics of VOQL based on visual variables. We carefully design the language constructs of VOQL*to reflect the syntax of OOPC, so that the constructs such as visual variables, visual elements, simple terms, structured terms,basic formulas , formulas, and query expressions in VOQL*are hierarchically and inductively constructed as those of OOPC. Most important, we formally define the semantics of each language construct of VOQL*by induction using OOPC. Because of the well-defined syntax and semantics, queries in VOQL*are clear, concise, and intuitive. We also provide an effective procedure to translate queries in VOQL*into those in OOPC. We believe that VOQL*is the first visual query language with the well-defined syntax reflecting the syntactic structure of logic and semantics formally defined by induction.

This paper describes the Kaleidoquery visual query language for object databases and its comparative evaluation with object query language (OQL). The design philosophy behind the filter flow nature of Kaleidoquery and each of the language's constructs is described, and examples are given that allow comparisons to be made with OQL. This is followed by a description of an experiment with the Kaleidoquery and OQL languages. Two groups of subjects, programmers and non-programmers, were taught aspects of OQL and Kaleidoquery, and then tested under experimental conditions. Results show that both groups answered significantly more correct queries using certain constructs of the Kaleidoquery language.

We describe the design, functionality and implementation of a data flow query language (DFQL), that graphically represents a query as a directed acyclic data flow graph. The language is well suited for application domains such as scientific databases, where data analysis and visualization need to be tightly coupled with data retrieval, and the relationships between the entities are ill-defined. DFQL differs from most query languages in that it is functional rather than declarative. By adopting a functional approach, DFQL seamlessly combines data retrieval, analysis and visualization operations into a single query. We have implemented this language for a scientific database used in a long term data-intensive pavement research project.

We present the hybrid query language HQL/EER for an Extended Entity-Relationship model. As its main characteristic, this language allows a user to usebothgraphical and textual elements in the formulation of one and the same query. We demonstrate the look-and-feel of this query language by means of examples, and show how syntax and semantics of this language are formally defined using programmed graph rewriting systems. Although we present the language in the context of the EER model, the concept of hybrid languages is applicable in the context of other database models as well. We illustrate this claim by discussing a prototype implementation of a Hybrid Query Tool based on an object-oriented approach, namely the Object Modeling Technique (OMT).

This paper presents a graphical query language for Geographic Information Systems, called Cigales. The basic idea of this language is to express a query by drawing a pattern corresponding to the results the user wants to be displayed. This drawing is in accordance with the user's representation of the real world. A set of active icons models graphical forms. These graphical forms are the representation of geometric objects such as line, area, and operations such as inclusion, intersection… The graphical query is then translated into a functional language. This intermediate language guarantees the independence of Cigales from the Data Management System. The user does not worry about physical storage of data and does not have to learn a new language. The functional expression is optimized and translated into specific Data Management System orders (i.e. extended SQL). This paper also describes an extended SQL of a geographic DBMS which was used as a first platform for the implementation of Cigales. The advantages and limits of using a graphical approach is then analysed.

The problem of formalization for visual languages has been identified as an important one. We present in this paper a formal definition of both the syntax and semantics of Gql, a declarative graphical query language based on the functional data model. In Gql a query is fully and unambiguously represented by a single diagram and the user interaction is kept distinct from the language itself. In our approach for formalization we abstract from the world of graphics and concentrate on a world of sets and functions, called the base structure, which represent the various elements of the language. The syntactical definition of the language is completed by defining a set of rules that a base structure instance must satisfy, in order for it to correspond to a legal Gql query. The semantics of the language is given via a functionally defined, syntax-directed translation from Gql queries (represented as base structure instances) to list comprehensions. Finally, a form of attribute grammar is used in conjunction with the previous definitions for specifying in a single formalism both the syntax and semantics of Gql.

The query language Graquala, described and discussed here, is designed for a geographical information system. The basic map data structure to which Graquala has been adapted is a homogeneous raster-based structure of run-length-code (RLC) type. Because of the homogeneity of the map data structure, queries can be applied in a more or less generic way; that is, queries can be applied to all map data regardless of their type. For this reason it has been possible to design a visual data-flow query language that allows compound queries which can become quite complex. In this work, Graqula and some elements of its environment, including a brief overview of the basic map data structure, will be discussed.

A graphical query language is a visual language which is intended as a database interface and which employs visual metaphors in order to express the semantics of a database language. The TableTalk graphical query language assumes an objectoriented data model and is based upon the notion of a functional query language. TableTalk is a diagrammatic language which uses a variety of visual representations to capture the semantics of a functional query language, including vertical and horizontal juxtapositioning of elements and spatial embedding. This paper presents an introduction to the TableTalk language as well as a description of how TableTalk might be used in a graphical query system.