A Simpler and Semantic Multidimensional Database Query Language to Facilitate Access to Information in Decision-making

OLAP and multidimensional database technology have contributed significantly to speed up and build confidence in the effectiveness of methodologies based on the use of management indicators in decision-making, industry, production, and services. Although there are a wide variety of tools related to the OLAP approach, many implementations are performed in relational database systems (R-OLAP). So, all interrogation actions are performed through queries that must be reinterpreted in the SQL language. This translation has several consequences because SQL language is based on a mixture of relational algebra and tuple relational calculus, which conceptually responds to the logic of the relational data model, very different from the needs of the multidimensional databases. This paper presents a multidimensional query language that allows expressing multidimensional queries directly over ROLAP databases. The implementation of the multidimensional query language will be done through a middleware that is responsible for mapping the queries, hiding the translation to a layer of software not noticeable to the end-user. Currently, progress has been made in the definition of a language where through a key statement, called aggregate, it is possible to execute the typical multidimensional operators which represent an important part of the most frequent operations in this type of database.

Programmatic implementation of the Dijkstra algorithm in the Transact-SQL language using relational algebra

The article is devoted to the topical issue of data processing in the database management systems. It presents a solution to the problem of finding paths in a graph using Dijkstra’s algorithm, set as a sequence of relational operations and functions of the Transact-SQL language. The efficiency of the known information system architectures and the impact of various ways of distributing functions between system components are reviewed. The article describes features of the relational algebra and the Transact-SQL operations, and provides a brief description of Dijkstra’s algorithm. For its programmatic implementation, several stages are defined, for each of which a formal description of the relational operations performed on it is given. The outputs of these operations are shown using the example of the database tables, and the algorithm to find the final path is given. The issues of the proposed method’s productivity and security of programmatic implementation of the path search in a graph are discussed separately.

The Development of SQL Language Skills in Data Definition and Data Manipulation Languages Using Exercises with Quizizz for Students' Learning Engagement

<p>The exercise is one of the educational activities that help students to understand and achieve their learning goals. Quizizz is a great online tool which helps students to check their knowledge and learning progress. In this paper, the researcher applied the SQL (Structured Query Language) skill in data definition language (DDL) and data manipulation language (DML) exercises and engaged the student’s learning by using Quizizz on students’ Introduction to Database course. The exercises and Quizizz were employed to an experimental group and a conventional teaching method was used for the control groups. The groups of students were of the heterogeneous level. Using the DDL and DML exercises, the students can review the knowledge repeatedly by doing exercises. In addition, the student can learn something from doing quizzes via Quizizz. The study on SQL exercises were conducted in order to improve students' achievement in DDL and DML. The purposes of this research were to 1) compare the students’ pre-test and post-test achievement using Quizizz and 2) investigate the students’ satisfaction while using SQL language skill exercises and Quizizz. The sample consisted of 34 students who enrolled in an Introduction to Database course in semester 1 of the academic year 2017. The students applied SQL language skill exercises when working on SQL assignment statement syntax. The students' pre-tests and post-tests were assessed. Percentage, mean and standard deviation, and average score (t-test) were used to analyze the data. The result showed that the students’ scores from the post-test was higher than the pre-test. There was a statistical significance at the level of 0.05. According to the result, it indicated that the students’ achievement was improved by the implementation. The students' satisfaction with the SQL language skill exercises and Quizizz was at a highest level (X = 4.58, S.D. = 0.54).</p>

Application of the Spatial Database for Shoreline Change Analysis and Visualisation: Example from the Western Polish Coast, Southern Baltic Sea

The main aim of the study was to introduce a spatial database application for the estimation of changes in shoreline position. The open-source PostgreSQL database system with the PostGIS spatial extension was used as the data store for digitalised shorelines. The solution to calculations of the shoreline changes was based on the functions written in the PL/SQL language and geospatial functions provided by the PostGIS extension. The traditional baseline and transects method was used to quantify the distances and rate of shoreline movement. Outputs of the calculations were stored in the database table and simply visualised using graphical functions in the R software environment or in GIS Desktop software. The advantage of presented method is the application of SQL language in the analysis of the relation between the geometry of shorelines stored in the database table, which, compared to other similar solutions, gives the user fully open, simple analytical code and enable selecting custom parameters of analysis, modifying code and performing additional calculations.

How Do the Engineer Students Learn the SQL Language?

In the teaching of database management the teaching of standardized SQL language cannot be avoided. Until the appearance of e-learning education systems we could only support the learning of SQL language with showing example queries. Using e-learning education systems in the education enables using tests, tutorials, teacher feedbacks which facilitate the learning of SQL language. But still these education tools can not ensure that students receive error message and assessment for correctness of the query edited in database management system in their native language after running the SQL query. In order to accomplish these two latter purposes we wrote a SQL tutoring system which was used from 2012�??s autumn by the students. In the paper we describe the problems of learning the SQL language, the supporting methods for learning before installation of the SQL tutoring system and with analysis of data of log file of the SQL tutoring system the manner of students�?? learning of SQL.