The significance of joins in relation theory
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Date
2016
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UMT.Lahore
Abstract
Teaching joins to beginners is a complex task .The join is one of the most significant query operations of relational database. Joins helps in accessing the data from one or more relations based on Cartesian product. Join operators are used for access the data from relations. Join operators are the most important concept and skill for students taking a course in database design and implementation specifically those majoring in CS/IT/SE/EE/BBIT.All of the database textbooks partially cover the topics of Joins and operators but the full set of join operators are not fully exemplified. The concept of join is most challenging operation for students to implement efficient and effective relational algebra expression. The join is an expensive operation in term of I/O. A lot of research has been applied to the optimization of join query operation. Usually query execution takes more time than query optimization. In case of highly normalized relation, very large databases, frequency of join operation is very high. To perform join query more efficiently the selection of join operators for optimal result is very important. With the best of our knowledge, no text or curriculum fully cover the topics of join and there related operations, it creates deficiency in students to write efficient and effective queries, on industry real life problems. Occasionally it is very tough for readers, research scholars, students to learn and teach Join operators.
In this research we propose the taxonomy of joins with our possible sub topics which cover logical and physical join operators. Our research consist of three factors— taxonomy of join operators, query training and the use of formative and summative assessments—on learning to relational algebra and SQL were investigated. This study depend an iterative methodological approach is completed across two semester. The study use matrix for evaluation of student learning in query execution in the SQL, we used evaluation parameters such as query success and time taken by students in executing query. The factors affecting the student learning in database are identified and analyzed. The findings of the research provided enough evidence that using simple approach (relational algebra to SQL) instead of more complex one (SQL to relational algebra) facilitated student’s learning of database concepts. Finally, it was observe that summative and formative feedback in the context of database system based on multiple parameters. The findings of this research helped in identifying the gaps in the field of teaching and learning database specifically joins.
The aim of this research is the evaluation of join operators and query optimization in SQL for teachers, learners to improve their database concepts, implements the join operators in Relational database, visualize join table’s diagrams with real life practical examples, and define the best sequence of teaching. I also clarified which types of join require ANSI Syntax and which could be constructed with traditional syntax.