Pathfinder: XQuery - The Relational Way

Relational query processors are probably the best understood (as well as the best engineered) query engines available today. Although carefully tuned to process instances of the relational model (tables of tuples), these processors can also provide a foundation for the evaluation of "alien" (non-relational) query languages: if a relational encoding of the alien data model and its associated query language is given, the RDBMS may act like a special-purpose processor for the new language

First-Class Functions for First-Order Database Engines

We describe Query Defunctionalization which enables off-the-shelf first-order database engines to process queries over first-class functions. Support for first-class functions is characterized by the ability to treat functions like regular data items that can be constructed at query runtime, passed to or returned from other (higher-order) functions, assigned to variables, and stored in persistent data structures. Query defunctionalization is a non-invasive approach that transforms such function-centric queries into the data-centric operations implemented by common query processors. Experiments with XQuery and PL/SQL database systems demonstrate that first-order database engines can faithfully and efficiently support the expressive "functions as data" paradigm.Comment: Proceedings of the 14th International Symposium on Database Programming Languages (DBPL 2013), August 30, 2013, Riva del Garda, Trento, Ital

A GPFCSP-Based Fuzzy XQuery Interpreter

Nowadays XQuery has become the strongest standard for querying XML data. However, most of the real world information is in the form of imprecise, vague, ambiguous, uncertain and incomplete values. That is why there is a need for a flexible query language in which users can formulate queries that arise from their own criteria. In this paper, we propose an implementation of the Fuzzy XQuery - an extension of the XQuery query language based on the fuzzy set theory. In particular, we provide priority, threshold and fuzzy expressions for handling flexible queries. In addition, we have implemented an interpreter for this language by using the GPFCSP concept in Java and eXist-db environment

An XQuery-based Model Transformation Language

In this paper we propose a framework for model transformation in XQuery. Our proposal aims to provide the elements for using XQuery as a transformation language. With this aim, our framework provides a mechanism for automatically obtaining an XQuery library for a given meta-model. Meta-models are defined as XML schemas, and the XQuery library serves to query and create elements of an XML Schema. Transformations abstract from XML representation, in the sense of, elements from meta-models are encapsulated by XQuery functions. We have also studied how to use our framework for model validation. Source and target models and transformations are validated by considering constraints. The framework has been tested with a case study of transformation in UML, where the XML-based representation of models is achieved by the standardized language XMI

On Region Algebras, XML Databases, and Information Retrieval

This paper describes some new ideas on developing a logical algebra for databases that manage textual data and support information retrieval functionality. We describe a first prototype of such a system

Exploiting XML Technologies in Medical Information Systems

Integration of clinical research data and routine care data, in order to streamline the process of conducting clinical studies, has been a problem for quite a while now. The Single Source project at the University of Münster aims at contributing to this area. The approach is based on a vast usage of XML technology together with a novel integration architecture. The emphasis in this paper is on the former: The seamless usage of XML technology throughout the entire application is presented, and mismatches of programming paradigms are averted by exploiting the features of XML, XQuery and XForms. In particular, this is demonstrated by the example of a component used for handling forms, by how it is built and used in the entire scenario

Using a Semi-Realistic Database to Support a Database Course

A common problem for university relational database courses is to construct effective databases for instructions and assignments. Highly simplified ‘toy’ databases are easily available for teaching, learning, and practicing. However, they do not reflect the complexity and practical considerations that students encounter in real-world projects after their graduation. On the other hand, production databases may contain too much domain nuances and complexity to be effectively used as a learning tool. Sakila is a semi-realistic, high quality, open source, and highly available database provided by MySQL. This paper describes the use of Sakila as a unified platform to support instructions and multiple assignments of a graduate database course for five semesters. Based on seven surveys with 186 responses, the paper discusses our experience using Sakila. We find this approach promising, and students in general find it more useful and interesting than the highly simplified databases developed by the instructor, or obtained from textbooks. We constructed a collection of 124 problems with suggested solutions on the topics of database modeling and normalization, SQL query, view, stored function, stored procedure, trigger, database Web-driven application development with PHP/MySQL, Relational Algebra using an interpreter, Relational Calculus, XML generation, XPath, and XQuery. This collection is available to Information Systems (IS) educators for adoption or adaptation as assignments, examples, and examination questions to support different database courses

Development of query language for retrieval, integration and presentation of data

The aim of this work was to improve the system Algator in the part, which deals with the analysis and presentation of data. First, we compared some query languages to find the most suitable for use in the system Algator. Algator stores data in a specific format, and the data are always combined in the same fashion. Therefore, special query language is more suitable because it can take advantage of these properties. We determined the simplified syntax of SQL and used in the system Algator. User interface and converter from JSON format to a simplified SQL and vice versa has been developed. Execution of queries has been optimized because some inquiries run too long. Functionality of calculated fields has been added, which allows to add additional fields that are calculated from other fields

Alternate syntax for XSLT

XSLT is a transform language for XML that is defined over XML. In other words, XSLT is a language that performs transforms on XML documents, and XSLT programs are themselves XML documents. While XSLT is by nature a functional language, its definition as an XML application obfuscates this fact [15]. Previous research projects have taken the XML-Infoset and provided an alternate syntax in the form of S-expressions, along with providing languages to perform transformations of the new representation in manners similar to that of XSLT. For example, SXML / SXSLT performs this function by embedding said languages in Scheme [9]. XLove applies modern principles of object-oriented design, namely design patterns, to this problem. Xl is an alternate syntax for the XML-Infoset. It maintains a clear distinction between attributes and elements (while having a concise notation for namespaces). The syntax is built into a representation over the Document Object Model by observers responding to parsing events. Xlt is an alternate syntax for XSLT designed to emphasize the functional nature of the language. A set of visitors transforms the input Document Object Model tree into an output tree by mapping the Xlt abstract syntax tree to XSLT. The resultant document is a valid XSLT program over the Document Object Model which can than be directly executed or output as an XML file