Bogdan D. Czejdo

A graphical data manipulation language for an extended entity-relationship model

A user can formulate database queries and updates graphically, by manipulating schema diagrams. The authors based the graphical data manipulation interface on the entity-relationship (ER) model because of its widespread use and increasing popularity. They use an extended ER model incorporating various forms of generalization and specialization, including subset, union and partition relationships. They call their model the extended conceptual entity-relationship or ECER model. A comparison with other graphical entity-relationship interfaces is included.<<ETX>>

An approach to schema integration and query formulation in federated database systems

A language is introduced in which both schema integration and query formulation for federated database systems can be performed. The relational model is augmented with connectors that impose predicate conditions over attributes of relations either at the same or different sites. The relational model with connectors has a natural diagrammatic representation, and thus, the language has a graphical user interface. The theoretical foundation for the graphical language is algebraic. Bach algebraic operator maps a diagram (of relations with connectors) into another diagram, and every diagram represents a possible user query. Operators specifically designed to operate on incompatible schemas are introduced and formally defined. Possible domain incompatibilities are resolved by using extended abstract data types.

Integration of database systems using an object-oriented approach

With ever-increasing amounts of data being stored on computers, there is a growing demand for systems that will support convenient access to data that are distributed across multiple databases. The authors describe an object-oriented language which supports the definition and use of partially integrated views of a collection of autonomous database systems. They provide a classification of incompatibilities between autonomous databases, in order to define multi-database classes and messages and the subclass/superclass hierarchy. User queries are expressed in a uniform object-oriented language based on Smalltalk.<<ETX>>

Graphical query formulation for an entity-relationship model

Abstract A query language is defined in which users graphically manipulate entity-relationship (ER) diagrams to formulate queries. The theoretical foundation for the graphical language is algebraic. Each algebraic operator maps an ER diagram to an ER diagram, and every ER diagram represents a possible user query. A set of operators is formally defined and a suggested interactive implementation is given. The set of algebraic operators is both entity-set conservative, which guarantees that a user can interpret any transformed diagram in terms of known entity sets, and relationally complete, which guarantees an acceptable level of retrieval power.

Integrating sets, rules, and data in an object-oriented environment

The Tanguy knowledge-base management system, which integrates rule-base, database, and object-oriented paradigms to capture the advantages of each, is discussed. Tanguy provides set-oriented interfaces, data-driven production rules, and permanent object storage in a C++ environment. The need for integration of the three paradigms is reviewed. The Tanguy architecture, the data model used in Tanguy, and Tanguys production rules are described.<<ETX>>

A visual query language for an ER data model

A graphical representation of an ER (entity-relationship) data model and its application to interactive visual query languages are presented. A method for implementing an ER query interface for a relational database management system is outlined. The approach is based on graphical representation and interactive manipulation of ER database schemas. During the process of query formulation the information needed to generate an equivalent SQL expression for a relational database is accumulated. The sample interactions between the user and system are given. The graphical query formulation process is formally defined. Formal definitions that provide the basis for an efficient visual query language implementation are presented.<<ETX>>

Automatic generation of ontology based annotations in XML and their use in retrieval systems

The unprecedented growth in the volume of online information has led to an information explosion which has made producing queries over this information difficult. In this paper, we examine an automated mechanism which allows users to access this information in a structured manner by analyzing unstructured text by domain-specific ontologies, annotating these documents using XML tags and using specific query processing techniques. Our approach is to use focused linguistic techniques over a limited context of an ontology for the identification and annotation of basic concepts and relationships in textual documents. These annotated documents can then be related to other structured information sources specified over similar ontologies.

Design and implementation of an interactive graphical query interface for a relational database management system

A graphical query interface, implemented as a front-end to a relational database management system, is described. A user manipulates database schema diagrams by graphically invoking operators that specify a query. During the process of query formulation the information needed to generate an equivalent structured query language (SQL) expression is accumulated. The formal definitions of the mapping of graphical operators into SQL are given, and sample interactions between a user and the system are shown.<<ETX>>

View specification and manipulation for a semantic data model

Abstract Semantic data models are increasing in popularity and use, but they are also becoming increasingly complex and difficult to manage. In this paper we extend the definition of a semantic data model to give users the power to specify and manipulate views. Our model supports both high-level object-class views and high-level relationship-set views. To define these views, we extend the traditional method of view definition (through query formulation) to also include view definition by a dominant object class, by an independent object class, and by a relational object class. A set of operators to specify and manipulate views is also defined. These operators allow a user to create and destroy views, implode and explode views, hide and expose semantic-model elements. We also provide algorithms to extract an instance graph for a high-level object in a semantic-model view and to transform a semantic-model view hierarchy into an equivalent atomic model. Implications and applications of views in our model are also discussed.

Integration of database systems and Smalltalk

The authors present an object-oriented data model, that allows uniform specification of database requests and application programs. The user interface is based on Smalltalk, and the object-oriented data model is represented in terms of classes and messages. Techniques are discussed for implementing such a model on top of an underlying relational database system. Those parts of application programs that cannot be translated into a relational language are handled by a Smalltalk processor. The semantics of database requests is defined in terms of a meta-model and meta-messages, using an object-oriented approach. Hence we derive rules for translation of database requests into SQL queries over a binary relational view.<<ETX>>