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Aggregation in ER Diagram: A Comprehensive Guide
Author: Dr. Anya Sharma, PhD in Database Management Systems, 15+ years experience in database design and development, author of "Database Design Demystified."
Publisher: TechVerse Publishing, a leading publisher of technical guides and manuals specializing in software engineering and database technologies.
Editor: Mr. David Lee, Senior Database Architect with 20 years of experience in enterprise database solutions.
Keywords: aggregation in ER diagram, ER diagram aggregation, database design, entity relationship diagram, UML, relationships, weak entities, composition, association, database modeling
Summary: This comprehensive guide explores the concept of aggregation in ER diagrams, a crucial aspect of database design. We delve into the different types of aggregation, best practices for its implementation, and common pitfalls to avoid. The guide provides practical examples and clarifies the distinctions between aggregation and other relationship types, like composition and association. Understanding aggregation is critical for building efficient and well-structured databases.
What is Aggregation in ER Diagram?
Aggregation in an Entity-Relationship Diagram (ERD) represents a "has-a" relationship between entities, indicating a "whole-part" relationship where one entity is composed of multiple other entities. Unlike a simple association, aggregation implies a weaker form of ownership. The "whole" can exist independently of its "parts," although the parts may often be strongly associated with the whole. This is represented graphically in the ERD using a filled diamond on the "whole" entity's side of the relationship line.
Example: Consider a university and its departments. A university has many departments, but a department can exist independently of the university (though it might not be very meaningful). This is an aggregation relationship.
Types of Aggregation in ER Diagrams
While the filled diamond universally signifies aggregation, the strength of the relationship can vary. Two key distinctions are crucial:
Weak Aggregation: The "parts" can exist independently of the "whole." This is the most common type of aggregation and is illustrated by the university-department example. The department can exist even if it isn't associated with a particular university.
Strong Aggregation (Composition): This represents a stronger form of aggregation where the "parts" cannot exist independently of the "whole." If the "whole" is deleted, the "parts" are also deleted. For example, a car is composed of an engine, wheels, and other parts. If the car is scrapped, the engine, wheels, etc., are also discarded. Composition is often represented by a filled diamond with a slightly darker shade, although this distinction isn't strictly enforced in all diagramming tools.
Best Practices for Using Aggregation in ER Diagrams
Clearly Define the Relationship: Ensure the "has-a" relationship is accurately represented. Analyze the dependencies between the entities before choosing aggregation.
Consistency is Key: Maintain a consistent style for representing aggregation throughout your ERD.
Avoid Overuse: Aggregation should only be used when appropriate. Overusing it can complicate the diagram and obscure the essential relationships.
Consider Cardinality: Specify the cardinality (one-to-one, one-to-many, many-to-many) of the aggregation relationship to clarify the number of "parts" associated with a "whole."
Use Appropriate Notation: Employ the standard notation for aggregation (filled diamond) consistently.
Document Your Decisions: Explain your reasoning for choosing aggregation over other relationship types.
Common Pitfalls to Avoid
Confusing Aggregation with Association: Aggregation implies a stronger relationship than simple association. A simple association does not imply ownership or dependence.
Incorrect Cardinality: Misrepresenting the cardinality can lead to database inconsistencies and errors.
Over-Aggregation: Creating unnecessary levels of aggregation complicates the design and makes it harder to understand.
Ignoring the Implications of Deletion: Failing to consider the impact of deleting the "whole" entity on the "parts" can lead to data loss or inconsistencies, particularly in strong aggregation (composition).
Aggregation vs. Association vs. Composition
The differences between these three types of relationships are frequently a source of confusion. Here's a summary table to clarify:
| Relationship Type | Description | Diagram Symbol | "Parts" existence independent of "Whole"? | Deletion of "Whole" affects "Parts"? |
|---|---|---|---|---|
| Association | General relationship between entities | Line | Yes | No |
| Aggregation | "Has-a" relationship, weaker form of ownership | Filled diamond | Yes | Usually no, but may depend on database implementation |
| Composition | "Has-a" relationship, stronger form of ownership | Filled, darker diamond (often) | No | Yes |
Conclusion
Mastering aggregation in ER diagrams is essential for creating robust and well-structured databases. By carefully considering the nature of the relationships between entities and following best practices, you can design effective databases that meet the needs of your applications. Understanding the distinctions between aggregation, association, and composition is critical for avoiding common pitfalls and creating a clear and concise ERD.
FAQs
1. What is the difference between aggregation and composition? Aggregation is a weaker "has-a" relationship where the parts can exist independently; composition is stronger, where the parts cannot exist without the whole.
2. How is aggregation represented graphically in an ERD? A filled diamond on the "whole" entity's side of the relationship line.
3. Can I use a different symbol for aggregation in my ERD? While a filled diamond is standard, maintaining consistency within your diagram is crucial. Avoid deviating from common notation unless absolutely necessary.
4. What are the implications of deleting a "whole" entity in an aggregation relationship? In weak aggregation, the parts usually remain. In composition, the parts are deleted as well.
5. How do I choose between aggregation and association? If there’s a clear ownership or "has-a" relationship, consider aggregation. If the connection is more general, use association.
6. What is cardinality in the context of aggregation? Cardinality specifies how many "parts" can be associated with one "whole" (e.g., one-to-many, many-to-many).
7. Can aggregation be used with weak entities? Yes, weak entities can participate in aggregation relationships, often as "parts."
8. How do I model recursive aggregation? Recursive aggregation involves an entity aggregating instances of itself. This is represented by a self-referencing relationship with a filled diamond.
9. What tools can I use to create ER diagrams with aggregation? Many tools support ERD creation, including Lucidchart, draw.io, ERwin Data Modeler, and more. Choose a tool that suits your needs and experience.
Related Articles:
1. Entity Relationship Diagrams (ERDs): A Beginner's Guide: A foundational introduction to ERDs, covering basic concepts and notations.
2. Understanding Cardinality in ER Diagrams: A deep dive into cardinality, its importance in database design, and how it applies to various relationship types.
3. Weak Entities in ER Diagrams: Explores the concept of weak entities and how they relate to other entities in the database schema.
4. Normalization in Database Design: Covers the process of organizing data to reduce redundancy and improve data integrity, which is closely linked to proper ERD design including aggregations.
5. Database Design Best Practices: A broader overview of best practices in database design, including considerations for ERD creation and the use of aggregation.
6. Introduction to UML Class Diagrams: Comparing and contrasting ERDs with UML class diagrams, and exploring the similarities and differences in representing aggregation.
7. Designing Databases for Scalability: Discusses design choices, including aggregation, that impact the scalability of a database system.
8. Common Mistakes in ER Diagram Design: Highlights common errors in ERD design, including misuse of aggregation, incorrect cardinality, and poor normalization.
9. Advanced ER Diagram Techniques: Covers more complex topics such as generalization/specialization and inheritance within ER diagrams, which often interact with aggregation.
| aggregation in er diagram: Entity-Relationship Approach - ER '93 Ramez A. Elmasri, 1994-07-28 This monograph is devoted to computational morphology, particularly to the construction of a two-dimensional or a three-dimensional closed object boundary through a set of points in arbitrary position. By applying techniques from computational geometry and CAGD, new results are developed in four stages of the construction process: (a) the gamma-neighborhood graph for describing the structure of a set of points; (b) an algorithm for constructing a polygonal or polyhedral boundary (based on (a)); (c) the flintstone scheme as a hierarchy for polygonal and polyhedral approximation and localization; (d) and a Bezier-triangle based scheme for the construction of a smooth piecewise cubic boundary. |
| aggregation in er diagram: Valuepack Thomas Connolly, 2005-08-01 |
| aggregation in er diagram: Entity-Relationship Approach - ER '94. Business Modelling and Re-Engineering Pericles Loucopoulos, 1994-11-30 This volume constitutes the proceedings of the 13th International Conference on the Entity-Relationship Approach, ER '94, held in Manchester, UK in December 1994. The ER '94 book is devoted to business modelling and re-engineering and provides a balanced view between research and practical experience. The 34 full revised papers presented are organized in sections on business process modelling, enterprise modelling, systems evolution, modelling integrity constraints, object-oriented databases, active databases, CASE, reverse engineering, information system modelling, schema coordination, and re-engineering. |
| aggregation in er diagram: Unified Modeling Language: Systems Analysis, Design and Development Issues Siau, Keng, Halpin, Terry, 2000-07-01 UML is a large and complex language, with many features in need of refinement or clarification, and there are different views about how to use UML to build systems. This book sheds light on such issues, by illustrating how UML can be used successfully in practice as well as identifying various problematic aspects of UML and suggesting possible solutions. |
| aggregation in er diagram: Database Management System Oracle Sql And Pl/Sql , 2009 |
| aggregation in er diagram: DATABASE MANAGEMENT SYSTEM ORACLE SQL AND PL/SQL PRANAB KUMAR DAS GUPTA, P. RADHA KRISHNA, 2013-10-18 Database Management System (DBMS) and Oracle are essentially a part of the curriculum for undergraduate and postgraduate courses in Computer Science, Computer Applications, Computer Science and Engineering, Information Technology and Management. The book is organized into three parts to introduce the theoretical and programming concepts of DBMS. Part I (Basic Concepts and Oracle SQL) deals with DBMS basic, software analysis and design, data flow diagram, ER model, relational algebra, normal forms, SQL queries, functions, subqueries, different types of joins, DCL, DDL, DML, object constraints and security in Oracle. Part II (Application Using Oracle PL/SQL) explains PL/SQL basics, functions, procedures, packages, exception handling, triggers, implicit, explicit and advanced cursors using suitable examples. This part also covers advanced concepts related to PL/SQL, such as collection, records, objects, dynamic SQL and performance tuning. Part III (Advanced Concepts and Technologies) elaborates on advanced database concepts such as query processing, file organization, distributed architecture, backup, recovery, data warehousing, online analytical processing and data mining concepts and their techniques. All the chapters include a large number of examples. To further reinforce the concepts, numerous objective type questions and workouts are provided at the end of each chapter. Key Features • Explains each topic in a step-by-step detail.• Includes about 300 examples to illustrate the concepts. • Offers about 400 objective type questions to quiz students on key points.• Provides about 100 challenging workouts that invite deeper analysis and interpretation of the subject matter. New to the Second Edition • The book reorganized into three parts for better understanding of DBMS concepts.• All the existing chapters thoroughly revised and eight new chapters added.• New chapters discuss Oracle PL/SQL advanced programming concepts, data warehousing, OLTP, OLAP and data mining concepts.• Additional examples, questions and workouts in each chapter. TEACHING AID MATERIAL Teaching Aid Material for all the chapters is provided on the website of PHI Learning, which can be used by the faculties/teachers for delivering lectures. Visit www.phindia.com/gupta to explore the contents. |
| aggregation in er diagram: Database Management Systems Rajesh Narang, 2018-02-28 The contents of this second edition have been appropriately enhanced to serve the growing needs of the students pursuing undergraduate engineering courses in Computer Science, Information Technology, as well as postgraduate programmes in Computer Applications (MCA), MSc (IT) and MSc (Computer Science). The book covers the fundamental and theoretical concepts in an elaborate manner using SQL of leading RDBMS—Oracle, MS SQL Server and Sybase. This book is recommended in Guwahati University, Assam. Realizing the importance of RDBMS in all types of architectures and applications, both traditional and modern topics are included for the benefit of IT-savvy readers. A strong understanding of the relational database design is provided in chapters on Entity-Relationship, Relational, Hierarchical and Network Data Models, Normalization, Relational Algebra and Relational Calculus. The architecture of the legacy relational database R system, the hierarchical database IMS of IBM and the network data model DBTG are also given due importance to bring completeness and to show thematic interrelationships among them. Several chapters have been devoted to the latest database features and technologies such as Data Partitioning, Data Mirroring, Replication, High Availability, Security and Auditing. The architecture of Oracle, SQL of Oracle known as PL/SQL, SQL of both Sybase and MS SQL Server known as T-SQL have been covered. KEY FEATURES : Gives wide coverage to topics of network, hierarchical and relational data models of both traditional and generic modern databases. Discusses the concepts and methods of Data Partitioning, Data Mirroring and Replication required to build the centralized architecture of very large databases. Provides several examples, listings, exercises and solutions to selected exercises to stimulate and accelerate the learning process of the readers. Covers the concept of database mirroring and log shipping to demonstrate how to build disaster recovery solution through the use of database technology. Contents: Preface 1. Introduction 2. The Entity-Relationship Model 3. Data Models 4. Storage Structure 5. Relational Data Structure 6. Architecture of System R and Oracle 7. Normalization 8. Structured Query Language 9. T-SQL—Triggers and Dynamic Execution 10. Procedure Language—SQL 11. Cursor Management and Advanced PL/SQL 12. Relational Algebra and Relational Calculus 13. Concurrency Control and Automatic Recovery 14. Distributed Database and Replication 15. High Availability and RAID Technology 16. Security Features Built in RDBMS 17. Queries Optimization 18. Architecture of a Hierarchical DBMS 19. The Architecture of Network based DBTG System 20. Comparison between Different Data Models 21. Performance Improvement and Partitioning 22. Database Mirroring and Log Shipping for Disaster Recovery Bibliography Answers to Selected Exercises Index |
| aggregation in er diagram: Domain-driven Design Eric Evans, 2004 Domain-Driven Design incorporates numerous examples in Java-case studies taken from actual projects that illustrate the application of domain-driven design to real-world software development. |
| aggregation in er diagram: Introduction to Database Systems: ITL Education Solutions Limited, 2008 Introduction to Database Systems deals with implementation, design and application of DBMS and complicated topics such as relational algebra and calculus, and normalization in a simplified way. |
| aggregation in er diagram: Conceptual Modeling - ER 2004 Paolo Atzeni, Wesley Chu, Hongjun Lu, Shuigeng Zhou, Tok Wang Ling, 2005-01-17 On behalf of the Organizing Committee, we would like to welcome you to the proccedings of the 23rd International Conference on Conceptual Modeling (ER 2004). This conference provided an international forum for technical discussion on conceptual modeling of information systems among researchers, developers and users. This was the third time that this conference was held in Asia; the?rst time was in Singapore in 1998 and the second time was in Yokohama, Japan in 2001. China is the third largest nation with the largest population in the world. Shanghai, the largest city in China and a great metropolis, famous in Asia and throughout the world, is therefore a most appropriate location to host this conference. This volume contains papers selected for presentation and includes the two keynote talks by Prof. Hector Garcia-Molina and Prof. Gerhard Weikum, and an invited talk by Dr. Xiao Ji. This volume also contains industrial papers and demo/poster papers. An additional volume contains papers from 6 workshops. The conference also featured three tutorials: (1) Web Change Management andDelta Mining: Opportunities andSolutions, by SanjayMadria, (2)A Survey of Data Quality Issues in Cooperative Information Systems, by Carlo Batini, and (3) Visual SQL - An ER-Based Introduction to Database Programming, by Bernhard Thalheim. |
| aggregation in er diagram: Introduction to Database Management System Satinder Bal Gupta, |
| aggregation in er diagram: Principles of Database Management Wilfried Lemahieu, Seppe vanden Broucke, Bart Baesens, 2018-07-12 Introductory, theory-practice balanced text teaching the fundamentals of databases to advanced undergraduates or graduate students in information systems or computer science. |
| aggregation in er diagram: Database Management Systems Dr.S.Sathappan, Mrs. .M.Prasanna Lakshmi, Mr.B.Srinivas, Mr. Janardhana Rao Alapati, 2022-05-01 Database Management Systems have written by Dr.S.Sathappan,Mrs.M.Prasanna Lakshmi,Mr.B Srinivas,Mr.Janardhana Rao Alapati |
| aggregation in er diagram: Big Data Analytics and Knowledge Discovery Matteo Golfarelli, Robert Wrembel, Gabriele Kotsis, A Min Tjoa, Ismail Khalil, 2021-09-04 This volume LNCS 12925 constitutes the papers of the 23rd International Conference on Big Data Analytics and Knowledge Discovery, held in September 2021. Due to COVID-19 pandemic it was held virtually. The 12 full papers presented together with 15 short papers in this volume were carefully reviewed and selected from a total of 71 submissions. The papers reflect a wide range of topics in the field of data integration, data warehousing, data analytics, and recently big data analytics, in a broad sense. The main objectives of this event are to explore, disseminate, and exchange knowledge in these fields. |
| aggregation in er diagram: Database Modeling and Design Toby J. Teorey, Sam S. Lightstone, Tom Nadeau, H.V. Jagadish, 2011-02-10 Database Modeling and Design, Fifth Edition, focuses on techniques for database design in relational database systems. This extensively revised fifth edition features clear explanations, lots of terrific examples and an illustrative case, and practical advice, with design rules that are applicable to any SQL-based system. The common examples are based on real-life experiences and have been thoroughly class-tested. This book is immediately useful to anyone tasked with the creation of data models for the integration of large-scale enterprise data. It is ideal for a stand-alone data management course focused on logical database design, or a supplement to an introductory text for introductory database management. - In-depth detail and plenty of real-world, practical examples throughout - Loaded with design rules and illustrative case studies that are applicable to any SQL, UML, or XML-based system - Immediately useful to anyone tasked with the creation of data models for the integration of large-scale enterprise data |
| aggregation in er diagram: Database Management System (DBMS)A Practical Approach Rajiv Chopra, 2010 Many books on Database Management Systems (DBMS) are available in the market, they are incomplete very formal and dry. My attempt is to make DBMS very simple so that a student feels as if the teacher is sitting behind him and guiding him. This text is bolstered with many examples and Case Studies. In this book, the experiments are also included which are to be performed in DBMS lab. Every effort has been made to alleviate the treatment of the book for easy flow of understanding of the students as well as the professors alike. This textbook of DBMS for all graduate and post-graduate programmes of Delhi University, GGSIPU, Rajiv Gandhi Technical University, UPTU, WBTU, BPUT, PTU and so on. The salient features of this book are: - 1. Multiple Choice Questions 2. Conceptual Short Questions 3. Important Points are highlighted / Bold faced. 4. Very lucid and simplified approach 5.Bolstered with numerous examples and CASE Studies 6. Experiments based on SQL incorporated. 7. DBMS Projects added Question Papers of various universities are also included. |
| aggregation in er diagram: The Entity-Relationship Model Peter Pin-Shan Chen, 2016-12-06 Excerpt from The Entity-Relationship Model: A Basis for the Enterprise View of Data The subject of the logical view of data has attracted considerable attention in the past ten years. However, most researchers have focused on the user View of data. The need for studying the enterprise view of data was not recognized until recently. Different users of a database may have different views of the database, but the enterprise should have a unique and consistent view of the database. This is particularly important in designing a logically meaningful and consistent database. The concept of the enterprise View of data is very useful in the database design process and in. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works. |
| aggregation in er diagram: Information Modelling and Knowledge Bases III Setsuo Ohsuga, 1992 Papers direct the focus of interest to the development and use of conceptual models in information systems of various kinds and aim at improving awareness about general or specific problems and solutions in conceptual modelling. |
| aggregation in er diagram: eBook: Database Systems Concepts 6e SILBERSCHATZ, 2010-06-16 eBook: Database Systems Concepts 6e |
| aggregation in er diagram: Database Management System (DBMS): A Practical Approach, 5th Edition Chopra Rajiv, This comprehensive book, now in its Fifth Edition, continues to discuss the principles and concept of Database Management System (DBMS). It introduces the students to the different kinds of database management systems and explains in detail the implementation of DBMS. The book provides practical examples and case studies for better understanding of concepts and also incorporates the experiments to be performed in the DBMS lab. A competitive pedagogy includes Summary, MCQs, Conceptual Short Questions (with answers) and Exercise Questions. |
| aggregation in er diagram: Handbook on Architectures of Information Systems Peter Bernus, Kai Mertins, Günter Schmidt, 2013-03-14 An authoritative source about methods, languages, methodologies and supporting tools for constructing information systems that also provides examples for references models. Its strength is the careful selection of each of the above mentioned components, based on technical merit. The second edition completely revises all articles and features new material on the latest developments in XML & UML. The structure follows the definition of the major components of Enterprise Integration as defined by GERAM (Generalised Enterprise Reference Architecture and Methodology). 1st edition sold about 600 copies since January 2003. |
| aggregation in er diagram: Introduction to DBMS Dr. Hariram Chavan, Prof. Sana Shaikh, 2022-05-10 Database and I: A unified view of the Database KEY FEATURES ● Explains database fundamentals by using examples from the actual world. ● Extensive hands-on practice demonstrating SQL topics using MySQL standards. ● All-inclusive coverage for systematic reading and self-study. DESCRIPTION The knowledge of Database Management Systems (DBMS) has become a de facto necessity for every business user. Understanding various databases and how it becomes an integral part of any application has been a popular curriculum for undergraduates. In this book, you will learn about database design and how to build one. It has six chapters meant to bridge the gap between theory and legit implementation. Concepts and architecture, Entity-relation model, Relational model, Structured Query Language, Relational database design, and transaction management are covered in the book. The ER and relational models are demonstrated using a database system from an engineering college and implemented using the MySQL standard. The final chapter explains transaction management, concurrency, and recovery methods. The final chapter explains transaction management, concurrency, and recovery methods. With a straightforward language and a student-centered approach, this book provides hands-on experience with MySQL implementation. It will be beneficial as a textbook for undergraduate students, and database specialists in their professional capacity may also use it. WHAT YOU WILL LEARN ● Acquire a firm grasp of the principles of data and database management systems. ● Outlines the whole development and implementation process for databases. ● Learn how to follow step-by-step normalization rules and keep your data clean. ● MySQL operations such as DDL, DML, DCL, TCL, and embedded queries are performed. ● Develop an understanding of how the transaction management and recovery system operates. WHO THIS BOOK IS FOR This book is ideal for anyone who is interested in learning more about Database Management Systems, whether they are undergraduate students, new database developers, or with some expertise. Programming foundations, file system ideas, and discrete structure concepts are recommended but not required. TABLE OF CONTENTS 1. Database System Concepts and Architecture 2. The Entity-Relationship Model 3. Relational Model and Relational Algebra 4. Structured Query Language and Indexing 5. Relational Database Design 6. Transactions Management and Concurrency and Recovery |
| aggregation in er diagram: Databases and Mobile Computing Daniel Barbará, Ravi Jain, N. Krishnakumar, 2007-08-29 Database and Mobile Computing brings together in one place important contributions and up-to-date research results in this important area. Databases and Mobile Computing serves as an excellent reference, providing insight into some of the most important research issues in the field. |
| aggregation in er diagram: The Practice of Enterprise Modeling Anne Persson, Janis Stirna, 2009-11-16 Enterprise modeling (EM) has gained substantial popularity both in the academic community and among practitioners. A variety of EM methods, approaches, and tools are being developed and offered on the market. In practice they are used for various purposes such as business strategy development, process restructuring, as well as business and IT architecture alignment and governance. PoEM 2009 – the second IFIP WG 8.1 Working Conference on The Practice of Enterprise Modeling took place in November in Stockholm, Sweden. The conference series is a dedicated forum where the use of EM in practice is addressed by bringing together researchers, users, and practitioners in order to develop a better understanding of the practice of EM, to contribute to improved EM practice as well as to share knowledge and experiences. PoEM 2009 attracted 41 submissions from many different parts of the world, out of which the Program Committee selected 17 high-quality papers. Among the authors of these papers we find both researchers and practitioners. The resulting program reflects the fact that the topic of EM encompasses human, organizational issues, as well as more technical aspects related to the development of information systems. The program was organized in six thematic sessions: ? Experiences in EM ? The process of modeling ? EM in information systems development ? Model quality and reuse ? EM for Services modeling ? New ventures in EM The program also featured two keynotes by experienced EM practitioners. Håvard D. |
| aggregation in er diagram: Hands On DATABASE 2000 MCQ Harry Chaudhary., 2018-04-08 Our 2000+ Database Management System questions and answers focuses on all areas of Database Management System subject covering 100+ topics in Database Management System. These topics are chosen from a collection of most authoritative and best reference books on Database Management System. One should spend 1 hour daily for 2-3 months to learn and assimilate Database Management System comprehensively. This way of systematic learning will prepare anyone easily towards Database Management System interviews, online tests, examinations and certifications. Highlights Ø 2000+ Multiple Choice Questions & Answers in Database Management System with explanations Ø Lots of MCQs with Database Management System code/programming snippet and its output Ø Every MCQ set focuses on a specific topic in Database Management System Who should Practice these Database Management System Questions? Ø Anyone wishing to sharpen their skills on Database Management System programming language Ø Anyone preparing for aptitude test in Database Management System (both objective type and coding written test) Ø Anyone preparing for interviews (campus/off-campus interviews, walk-in interview and company interviews) Ø Anyone preparing for entrance examinations and other competitive examinations Ø All – Experienced, Freshers and Students Randomly DBMS 600+ MCQ Set Questions & Answers 7 Randomly DBMS 100+ MCQ Set Questions & Answers 85 Relational Database and Database Schema MCQ Set 99 Keys. 102 Relational Query Operations and Relational Operators 105 SQL Basics and SQL Data Definition 108 SQL Queries 111 Basic SQL Operations. 115 Set Operations 119 Null Values Operations 122 Aggregate Functions and Nested Subqueries – 1 125 Aggregate Functions and Nested Subqueries – 2 128 Modification of Database 131 Join Expressions 135 Database Questions And Answers – Views 138 Database Questions And Answers Transactions 142 Integrity Constraints 145 SQL Data Types and Schemas 148 Authorizations 151 Access SQL from a Programming Language 154 Functions and Procedures 157 Triggers 161 Recursive Queries and Aggregation Features. 164 OLAP-(online analytical processing) 167 Relational Algebra 170 Tuple Relational Calculus & Domain Relational Calculus 173 The Entity-Relationship Model 176 Constraints 179 Entity-Relationship Diagrams 182 Reduction to Relational Schemas 185 Entity-Relationship Design Issues 189 Extended E-R Features 192 Querying Database Part-1 DDL 195 Querying Database Part-2 DML 199 Atomic Domains 203 Normal Forms 206 Functional-Dependency Theory 209 Algorithms for Decomposition 213 Multivalued Dependencies 216 Database Design Process 219 Application Programs and User Interfaces- 222 Web Fundamentals 225 Servlets and JSP 228 Application Architectures 231 Rapid Application Development 234 Application Performance 237 Application Security 240 Encryption and Its Applications 243 Physical Storage Media 246 Magnetic Disk and Flash Storage 249 RAID 252 Tertiary Storage 255 File Organisations 258 Organization of Records in Files 261 Data-Dictionary Storage 264 Database Buffer 267 Ordered Indices 270 Hashing techniques 273 Ordered Indexing and Hashing 276 Bitmap Indices 279 Index Definition in SQL. 282 Query Processing 285 Selection Operation 288 Sorting 291 Join Operations 294 Evaluation of Expressions 297 Transformation of Relational Expressions 300 Estimating Statistics of Expression Results 303 Materialized Views 306 Advanced Query Optimization 310 Transaction Concept 313 A Simple Transaction Model 316 Storage Structure 319 Transaction Atomicity and Durability 322 Querying Database Part -3 325 Querying Database Part– 4 328 Querying Database Part– 5 331 Implementation of Isolation Levels 334 Transactions as SQL Statements 338 Lock-Based Protocols 341 Deadlocks 344 Multiple Granularity 347 Multiversion Schemes 350 Snapshot Isolation 353 Insertion Deletion Predicate Reads 356 Concurrency in Index Structures 361 Failure Classification 364 Recovery 367 Buffer Management 370 Failure with Nonvolatile Storage 376 ARIES 376 Lock Release and Undo Operations 379 Remote Backup Systems 382 Typical Mix DBMS MCQ's Set. 385-405 |
| aggregation in er diagram: Entity-relationship Approach , 1992 |
| aggregation in er diagram: Database and Expert Systems Applications A Min Tjoa, Roland Wagner, 2012-12-06 Use and development of database and expert systems can be found in all fields of computer science. The aim of this book is to present a large spectrum of already implemented or just being developed database and expert systems. Contributions cover new requirements, concepts for implementations (e.g. languages, models, storage structures), management of meta data, system architectures, and experiences gained by using traditional databases in as many areas of applications as possibble (at least in the fields listed). The aim of the book is to inspire a fruitful dialogue between developement in practice, users of database and expert systems, and scientists working in the field. |
| aggregation in er diagram: System Engineering Analysis, Design, and Development Charles S. Wasson, 2015-11-16 Praise for the first edition: “This excellent text will be useful to everysystem engineer (SE) regardless of the domain. It covers ALLrelevant SE material and does so in a very clear, methodicalfashion. The breadth and depth of the author's presentation ofSE principles and practices is outstanding.” –Philip Allen This textbook presents a comprehensive, step-by-step guide toSystem Engineering analysis, design, and development via anintegrated set of concepts, principles, practices, andmethodologies. The methods presented in this text apply to any typeof human system -- small, medium, and large organizational systemsand system development projects delivering engineered systems orservices across multiple business sectors such as medical,transportation, financial, educational, governmental, aerospace anddefense, utilities, political, and charity, among others. Provides a common focal point for “bridgingthe gap” between and unifying System Users, System Acquirers,multi-discipline System Engineering, and Project, Functional, andExecutive Management education, knowledge, and decision-making fordeveloping systems, products, or services Each chapter provides definitions of key terms,guiding principles, examples, author’s notes, real-worldexamples, and exercises, which highlight and reinforce key SE&Dconcepts and practices Addresses concepts employed in Model-BasedSystems Engineering (MBSE), Model-Driven Design (MDD), UnifiedModeling Language (UMLTM) / Systems Modeling Language(SysMLTM), and Agile/Spiral/V-Model Development such asuser needs, stories, and use cases analysis; specificationdevelopment; system architecture development; User-Centric SystemDesign (UCSD); interface definition & control; systemintegration & test; and Verification & Validation(V&V) Highlights/introduces a new 21st Century SystemsEngineering & Development (SE&D) paradigm that is easy tounderstand and implement. Provides practices that are critical stagingpoints for technical decision making such as Technical StrategyDevelopment; Life Cycle requirements; Phases, Modes, & States;SE Process; Requirements Derivation; System ArchitectureDevelopment, User-Centric System Design (UCSD); EngineeringStandards, Coordinate Systems, and Conventions; et al. Thoroughly illustrated, with end-of-chapter exercises andnumerous case studies and examples, Systems EngineeringAnalysis, Design, and Development, Second Edition is a primarytextbook for multi-discipline, engineering, system analysis, andproject management undergraduate/graduate level students and avaluable reference for professionals. |
| aggregation in er diagram: Database Management Systems P.S. Gill, 2010-09-30 The book is intended to provide an insight into the DBMS concepts. An effort has been made to familiarize the readers with the concepts of database normalization, concurrency control, deadlock handling and recovery etc., which are extremely vital for a clear understanding of DBMS. To familiarize the readers with the equivalence amongst Relational Algebra, Tuple Relational Calculus, and SQL, a large number of equivalent queries have been provided. The concepts of normalization have been elaborated very systematically by fully covering the underlying concepts of functional dependencies, multi-valued dependencies, join dependencies, loss-less-join decomposition, dependency-preserving decomposition etc. It is hoped that with the help of the information provided in the text, a reader will be able to design a flawless database. Also, the concepts of serializabilty, concurrency control, deadlock handling and log-based recovery have been covered in full detail. An overview has also been provided of the issues related to distributed-databases. |
| aggregation in er diagram: Graph Representation Learning William L. William L. Hamilton, 2022-06-01 Graph-structured data is ubiquitous throughout the natural and social sciences, from telecommunication networks to quantum chemistry. Building relational inductive biases into deep learning architectures is crucial for creating systems that can learn, reason, and generalize from this kind of data. Recent years have seen a surge in research on graph representation learning, including techniques for deep graph embeddings, generalizations of convolutional neural networks to graph-structured data, and neural message-passing approaches inspired by belief propagation. These advances in graph representation learning have led to new state-of-the-art results in numerous domains, including chemical synthesis, 3D vision, recommender systems, question answering, and social network analysis. This book provides a synthesis and overview of graph representation learning. It begins with a discussion of the goals of graph representation learning as well as key methodological foundations in graph theory and network analysis. Following this, the book introduces and reviews methods for learning node embeddings, including random-walk-based methods and applications to knowledge graphs. It then provides a technical synthesis and introduction to the highly successful graph neural network (GNN) formalism, which has become a dominant and fast-growing paradigm for deep learning with graph data. The book concludes with a synthesis of recent advancements in deep generative models for graphs—a nascent but quickly growing subset of graph representation learning. |
| aggregation in er diagram: COMPSTAT F. de Antoni, N. Lauro, A. Rizzi, 2012-12-06 When dealing with the design or with the application of any technical system, which is not quite simple and trivial, one has to face to the problem to determine the allowable de viations of the system functions and the optimal vector of system parameter tolerances. The need for the solution of this problem is stimulated with various serious economic and maite nance aspects, between them the tendency to reach the minimal production cost, the maximal system operation reliability are the most frequent. Suppose that we are dealing with an system S, consisting of N components represented by the system parame ters xi' i = 1, 2 . . . N, which are arranged in certain structu re so, that the K, system functions F k' k = 1, 2 . . . IG , expres sing the considered system properties, fullfil the condition F-FO~ AF, /1/ \'Ihere F = l F k} Ie is the set of the actual system functions, FO = lFOk}~ is the set of the nominal system functions and A F = l A F k 1(;. } is the set 0 f the a 11 0 w a b 1 e s emf y s t u n c ion t s de viations. The set F depends besides the system structure also on the vector X = [Xi}N of the system parameters. Suppose, that the system structure is invariant. |
| aggregation in er diagram: Multimedia and Imaging Databases Setrag Khoshafian, Brad Baker, 1996 Affordable and mainstream manipulation of multimedia data types will lead to tremendous growth in imaging and multimedia data in general computing environments. Multimedia and imaging applications can now provide benefits to common business applications by integrating voice, sound, images, animation and digitized video. Ultimately, it will be possible to convert all information that is currently stored on paper, video and film into a digitized environment. This will allow users to organize, search and route multimedia objects over local and wide area networks in real time. The authors' introductory level presentation of this new class of data types supplies the database technology required for effective manipulation and storage. Multimedia and database experts, Khoshafian and Baker aptly illustrate the ability of multimedia database systems to concurrently share, access, and query large collections of multimedia information. They introduce the elemental concepts of object and relational databases and then apply them to multimedia and imaging databases. Fundamental database topics discussed include querying, transaction support, recovery, security, and storage. This book provides information essential to the incorporation of multimedia databases that will improve the quantity and quality of information manipulated by computer users in many areas including medicine, computer aided design, and information retrieval systems. |
| aggregation in er diagram: Sixth International Conferencew on Information Technology , |
| aggregation in er diagram: Conceptual Modeling - ER 2000 Alberto H.F. Laender, Stephen W. Liddle, Veda Storey, 2000-09-20 This book constitutes the refereed proceedings of the 19th International Conference on Conceptual Modeling, ER 2000, held in Salt Lake City, Utah, USA in October 2000. The 37 revised full papers presented together with three invited papers and eight industrial abstracts were carefully reviewed and selected from a total of 140 submitted papers. The book offers topical sections on database integration, temporal and active database modeling, database and data warehouse design techniques, analysis patterns and ontologies, Web-based information systems, business process modeling, conceptual modeling and XML, engineering and multimedia application modeling, object-oriented modeling, applying object-oriented technology, quality in conceptual modeling, and application design using UML. |
| aggregation in er diagram: Discrete Choice Methods with Simulation Kenneth Train, 2009-07-06 This book describes the new generation of discrete choice methods, focusing on the many advances that are made possible by simulation. Researchers use these statistical methods to examine the choices that consumers, households, firms, and other agents make. Each of the major models is covered: logit, generalized extreme value, or GEV (including nested and cross-nested logits), probit, and mixed logit, plus a variety of specifications that build on these basics. Simulation-assisted estimation procedures are investigated and compared, including maximum stimulated likelihood, method of simulated moments, and method of simulated scores. Procedures for drawing from densities are described, including variance reduction techniques such as anithetics and Halton draws. Recent advances in Bayesian procedures are explored, including the use of the Metropolis-Hastings algorithm and its variant Gibbs sampling. The second edition adds chapters on endogeneity and expectation-maximization (EM) algorithms. No other book incorporates all these fields, which have arisen in the past 25 years. The procedures are applicable in many fields, including energy, transportation, environmental studies, health, labor, and marketing. |
| aggregation in er diagram: UML and the Unified Process Favre, Liliana, 2006-10-23 Unified Modeling Language (UML), Unified Process (UP), and other information modeling methods are addressed in this scholarly consideration of the analysis, design, and development of web-based and enterprise applications. The most current research on conceptual, theoretical, and empirical issues of modeling for online business and static information is provided. |
| aggregation in er diagram: The Unified Modeling Language Martin Schader, Axel Korthaus, 2012-12-06 Most of the articles in this volume are revised versions of papers presented during the 1st GROOM-Workshop on the Unified Modeling Language (UML). GROOM (Grundlagen objektorientierter Modellierung) is a working group of the Gesellschaft fur Informatik (GI), the German Society of Computer Science. The workshop took place at the University of Mannheim (Germany) in October 1997; the local organizers were Martin Schader and Axel Korthaus, Department of Information Systems. The scientific program of the workshop included 21 talks, presented in German language on Friday, Oct. 10th, and Saturday, Oct. 11th, 1997. Researchers and practitioners interested in object-oriented software development, analysis and design of software systems, standardization efforts in the field of object technology, and particularly in the main topic of the workshop: ''Applications, State of the Art, and Evaluation of the Unified Modeling Language had the opportunity to discuss recent developments and to establish cooperation in these fields. The workshop owed much to its sponsors and supporters - University of Mannheim - Faculty of Business Administration, University of Mannheim - Sun Microsystems GmbH - Apcon Professional Concepts GmbH. Their generous support is gratefully acknowledged. In the present proceedings volume, papers are presented in three chapters as follows. |
| aggregation in er diagram: Transactions on Large-Scale Data- and Knowledge-Centered Systems I Abdelkader Hameurlain, Josef Küng, Roland Wagner, 2009-08-24 Data management, knowledge discovery, and knowledge processing are core and hot topics in computer science. They are widely accepted as enabling technologies for modern enterprises, enhancing their performance and their decision making processes. Since the 1990s the Internet has been the outstanding driving force for application development in all domains. An increase in the demand for resource sharing (e. g. , computing resources, s- vices, metadata, data sources) across different sites connected through networks has led to an evolvement of data- and knowledge-management systems from centralized systems to decentralized systems enabling large-scale distributed applications prov- ing high scalability. Current decentralized systems still focus on data and knowledge as their main resource characterized by: heterogeneity of nodes, data, and knowledge autonomy of data and knowledge sources and services large-scale data volumes, high numbers of data sources, users, computing resources dynamicity of nodes These characteristics recognize: (i) limitations of methods and techniques developed for centralized systems (ii) requirements to extend or design new approaches and methods enhancing efficiency, dynamicity, and scalability (iii) development of large scale, experimental platforms and relevant benchmarks to evaluate and validate scaling Feasibility of these systems relies basically on P2P (peer-to-peer) techniques and agent systems supporting with scaling and decentralized control. Synergy between Grids, P2P systems and agent technologies is the key to data- and knowledge-centered systems in large-scale environments. |
| aggregation in er diagram: Database Systems Paolo Atzeni, 1999 Covers the important requirements of teaching databases with a modular and progressive perspective. This book can be used for a full course (or pair of courses), but its first half can be profitably used for a shorter course. |
| aggregation in er diagram: High-Performance Web Databases Sanjiv Purba, 2000-09-21 As Web-based systems and e-commerce carry businesses into the 21st century, databases are becoming workhorses that shoulder each and every online transaction. For organizations to have effective 24/7 Web operations, they need powerhouse databases that deliver at peak performance-all the time. High Performance Web Databases: Design, Development, and |
Noob question: I setup port aggregation and it says LACP ... - Reddit
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About aggregation: Can someone explain aggregation when it
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Is Link Aggregation even worth it for my use case (or are the
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UML-Diagramme mit PlantUML
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the 2nd diagram! Policies policyid cost pname age Covers Dependents name Employees ssn lot Key constraint on Policies would mean policy can ... Aggregation? Note constraints of the ER …
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diagrams very similar to standard ER diagrams. Enhanced ER Model Enhanced entity-relationship diagrams are advanced database diagrams very similar to regular ER diagrams which …
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Conversion of ER model to Relational Model
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UML CLASS DIAGRAM OR ENTITY RELATIONSHIP …
Blaha, M [15], describes the UML Class diagram as a dialect of Chen’s original ER Diagram. Both of the notations are used to depict real world objects in terms of a static view of the system. …
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that should be represented in the ER diagram. Describe the wacky Movie world . Movie . Actor Movie Actor . Movie . ... • Aggregation: grouping part of a schema into a larger unit. 34 . In …
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1/30/2008 USC - CSCI585 - Spring 2008 - Farnoush Banaei-Kashani 5 Translating ER Diagrams with Key Constraints Map relationship to a table: Note that did is the key now! Separate tables …
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1 Class Diagrams and Entity Relationship Diagrams (ERD)
5.1.7 Review your diagram and fine tune it. Look for inconsistencies and errors. Fix them. Make sure you have captured everything required from the domain you are studying - that your …
