Database Fundamentals doc

Database Fundamentals Neeraj Sharma, Liviu Perniu, Raul F. Chong, Abhishek Iyer, Chaitali Nandan, Adi-Cristina Mitea, Mallarswami Nonvinkere, Mirela Danubianu A book for the community by the community F I R S T E D I T I O N Database Fundamentals 4 First Edition (November 2010) © Copyright IBM Corporation 2010. All rights reserved. IBM Canada 8200 Warden Avenue Markham, ON L6G 1C7 Canada This edition covers IBM ® DB2 ® Express-C Version 9.7 for Linux ®, UNIX ® and Windows ® . 5 Notices This information was developed for products and services offered in the U.S.A. IBM may not offer the products, services, or features discussed in this document in other countries. Consult your local IBM representative for information on the products and services currently available in your area. Any reference to an IBM product, program, or service is not intended to state or imply that only that IBM product, program, or service may be used. Any functionally equivalent product, program, or service that does not infringe any IBM intellectual property right may be used instead. However, it is the user's responsibility to evaluate and verify the operation of any non-IBM product, program, or service. IBM may have patents or pending patent applications covering subject matter described in this document. The furnishing of this document does not grant you any license to these patents. You can send license inquiries, in writing, to: IBM Director of Licensing IBM Corporation North Castle Drive Armonk, NY 10504-1785 U.S.A. For license inquiries regarding double-byte character set (DBCS) information, contact the IBM Intellectual Property Department in your country or send inquiries, in writing, to: Intellectual Property Licensing Legal and Intellectual Property Law IBM Japan, Ltd. 3-2-12, Roppongi, Minato-ku, Tokyo 106-8711 The following paragraph does not apply to the United Kingdom or any other country where such provisions are inconsistent with local law: INTERNATIONAL BUSINESS MACHINES CORPORATION PROVIDES THIS PUBLICATION "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF NON-INFRINGEMENT, MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Some states do not allow disclaimer of express or implied warranties in certain transactions, therefore, this statement may not apply to you. This information could include technical inaccuracies or typographical errors. Changes are periodically made to the information herein; these changes will be incorporated in new editions of the publication. IBM may make improvements and/or changes in the product(s) and/or the program(s) described in this publication at any time without notice. Any references in this information to non-IBM Web sites are provided for convenience only and do not in any manner serve as an endorsement of those Web sites. The materials at those Web sites are not part of the materials for this IBM product and use of those Web sites is at your own risk. IBM may use or distribute any of the information you supply in any way it believes appropriate without incurring any obligation to you. Database Fundamentals 6 The licensed program described in this document and all licensed material available for it are provided by IBM under terms of the IBM Customer Agreement, IBM International Program License Agreement or any equivalent agreement between us. Any performance data contained herein was determined in a controlled environment. Therefore, the results obtained in other operating environments may vary significantly. Some measurements may have been made on development-level systems and there is no guarantee that these measurements will be the same on generally available systems. Furthermore, some measurements may have been estimated through extrapolation. Actual results may vary. Users of this document should verify the applicable data for their specific environment. Information concerning non-IBM products was obtained from the suppliers of those products, their published announcements or other publicly available sources. IBM has not tested those products and cannot confirm the accuracy of performance, compatibility or any other claims related to non-IBM products. Questions on the capabilities of non-IBM products should be addressed to the suppliers of those products. All statements regarding IBM's future direction or intent are subject to change or withdrawal without notice, and represent goals and objectives only. This information contains examples of data and reports used in daily business operations. To illustrate them as completely as possible, the examples include the names of individuals, companies, brands, and products. All of these names are fictitious and any similarity to the names and addresses used by an actual business enterprise is entirely coincidental. COPYRIGHT LICENSE: This information contains sample application programs in source language, which illustrate programming techniques on various operating platforms. You may copy, modify, and distribute these sample programs in any form without payment to IBM, for the purposes of developing, using, marketing or distributing application programs conforming to the application programming interface for the operating platform for which the sample programs are written. These examples have not been thoroughly tested under all conditions. IBM, therefore, cannot guarantee or imply reliability, serviceability, or function of these programs. The sample programs are provided "AS IS", without warranty of any kind. IBM shall not be liable for any damages arising out of your use of the sample programs. References in this publication to IBM products or services do not imply that IBM intends to make them available in all countries in which IBM operates. If you are viewing this information softcopy, the photographs and color illustrations may not appear. 7 Trademarks IBM, the IBM logo, and ibm.com are trademarks or registered trademarks of International Business Machines Corp., registered in many jurisdictions worldwide. Other product and service names might be trademarks of IBM or other companies. A current list of IBM trademarks is available on the Web at “ Copyright and trademark information” at www.ibm.com/legal/copytrade.shtml. Java and all Java-based trademarks are trademarks of Sun Microsystems, Inc. in the United States, other countries, or both. Microsoft and Windows are trademarks of Microsoft Corporation in the United States, other countries, or both. Linux is a registered trademark of Linus Torvalds in the United States, other countries, or both. UNIX is a registered trademark of The Open Group in the United States and other countries. Other company, product, or service names may be trademarks or service marks of others. Table of Contents Preface 15 Who should read this book? 15 How is this book structured? 15 A book for the community 15 Conventions 15 What’s next? 16 About the Authors 17 Contributors 19 Acknowledgements 21 Chapter 1 - Databases and information models 23 1.1 What is a database? 23 1.2 What is a database management system? 23 1.2.1 The evolution of database management systems 24 1.3 Introduction to information models and data models 26 1.4 Types of information models 27 1.4.1 Network model 28 1.4.2 Hierarchical model 28 1.4.3 Relational model 29 1.4.4 Entity-Relationship model 30 1.4.5 Object-relational model 31 1.4.6 Other data models 32 1.5 Typical roles and career path for database professionals 32 1.5.1 Data Architect 32 1.5.2 Database Architect 32 1.5.3 Database Administrator (DBA) 33 1.5.4 Application Developer 34 1.6 Summary 34 1.7 Exercises 35 1.8 Review questions 35 Chapter 2 – The relational data model 37 2.1 Relational data model: The big picture 37 2.2 Basic concepts 38 2.2.1 Attributes 38 2.2.2 Domains 39 2.2.3 Tuples 40 2.2.4 Relations 40 2.2.5 Schemas 41 2.2.6 Keys 41 2.3 Relational data model constraints 44 2.3.1 Entity integrity constraint 44 2.3.2 Referential integrity constraint 45 2.3.3 Semantic integrity constraints 46 2.4 Relational algebra 49 Database Fundamentals 10 2.4.1 Union 49 2.4.2 Intersection 49 2.4.3 Difference 50 2.4.4 Cartesian product 51 2.4.5 Selection 52 2.4.6 Projection 53 2.4.7 Join 54 2.4.8 Division 56 2.5. Relational calculus 57 2.5.1 Tuple-oriented relational calculus 58 2.5.2 Domain-oriented relational calculus 59 2.6 Summary 60 2.7 Exercises 60 2.8 Review questions 62 Chapter 3 – The conceptual data model 65 3.1 Conceptual, logical and physical modeling: The big picture 65 3.2 What is a model? 67 3.2.1 Data model 67 3.2.2 Database model 67 3.2.3 Conceptual data model concepts 68 3.3 A case study involving a Library Management System - Part 1 of 3 77 3.3.1 Developing the conceptual model 77 3.4 Summary 85 3.5 Exercises 85 3.6 Review questions 85 Chapter 4 – Relational Database Design 89 4.1 The problem of redundancy 89 4.1.1 Insertion Anomalies 90 4.1.2 Deletion Anomalies 90 4.1.3 Update Anomalies 90 4.2. Decompositions 91 4.3. Functional Dependencies 92 4.4 Properties of Functional Dependencies 94 4.4.1 Armstrong’s Axioms 94 4.4.2 Computing the closure set of attributes 95 4.4.3 Entailment 96 4.5 Normal Forms 96 4.5.1 First Normal Form (1NF) 96 4.5.2 Second Normal Form (2NF) 98 4.5.3 Third Normal Form (3NF) 99 4.5.4 Boyce-Codd Normal Form (BCNF) 100 4.6 Properties of Decompositions 101 4.6.1 Lossless and Lossy Decompositions 102 4.6.2 Dependency-Preserving Decompositions 103 4.7 Minimal Cover 103 [...]... a set of software tools that control access, organize, store, manage, retrieve and maintain data in a database In practical use, the terms database, database server, Database Fundamentals 24 database system, data server, and database management systems are often used interchangeably Why do we need database software or a DBMS? Can we not just store data in simple text files for example? The answer lies... form then it is called a relational database When data is organized in a tree structure form, it is called a hierarchical database Data stored as graphs representing relationships between objects is referred to as a network database In this book, we focus on relational databases 1.2 What is a database management system? While a database is a repository of data, a database management system, or simply... and a reliable database Database software usage is pervasive, yet it is taken for granted by the billions of daily users worldwide Its presence is everywhere-from retrieving money through an automatic teller machine to badging access at a secure office location This chapter provides you an insight into the fundamentals of database management systems and information models 1.1 What is a database? Since... models 1.1 What is a database? Since its advent, databases have been among the most researched knowledge domains in computer science A database is a repository of data, designed to support efficient data storage, retrieval and maintenance Multiple types of databases exist to suit various industry requirements A database may be specialized to store binary files, documents, images, videos, relational data,... information needs 1.5.2 Database Architect This role is similar to a Data Architect, though constraints more towards a database solution A database architect is responsible for the following activities:  Gather and document requirements from business users and management and address them in a solution architecture  Share the architecture with business users and management  Create and enforce database and application... and implementation details It is critical for a database architect to keep pace with the various tools, database products, hardware platforms and operating systems from different vendors as they evolve and improve 1.5.3 Database Administrator (DBA) A database administrator (DBA) is responsible for the maintenance, performance, integrity and security of a database Additional role requirements are likely... increasingly important aspects 1.5.4 Application Developer A database application developer is a person in charge of developing applications that access databases An application developer requires knowledge of the following:  Integrated database application development environments (IDEs)  Database plug-ins for IDEs  SQL development tools  Database performance monitoring and debugging  Application... around database administration, application development and usage 1.6 Summary In this chapter, we discussed several database fundamental concepts starting with simple definitions of a database and extending to a database management system Then, we discussed information and data models such as the network, hierarchical, and relational models At the end of the chapter, various roles associated with the database. .. minimize the time and effort required to learn many of these new technologies This book helps new database professionals understand database concepts with the right blend of breadth and depth of information Who should read this book? This book is tailored for new database enthusiasts, application developers, database administrators, and anyone with an interest in the subject and looking to get exposure... logical manipulation of data in the context of their specific application Figure 1.1 illustrates the evolution of database management systems Chapter 1 - Databases and information models 25 Figure 1.1 Evolution of database management systems The above figure describes the evolution of database management systems with the relational model that provide for data independence IBM's System R was the first . Chapter 1 - Databases and information models 23 1.1 What is a database? 23 1.2 What is a database management system? 23 1.2.1 The evolution of database. Chapter 9 – Database Security 221 9.1 Database security: The big picture 221 9.1.1 The need for database security 222 9.1.2 Access control 224 9.1.3 Database