Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
CHAPTER 07 Storing Organizational Information – Databases McGraw-Hill/Irwin Copyright © 2013 by The McGraw-Hill Companies, Inc. All rights reserved. LEARNING OUTCOMES 1. Define the fundamental concepts of the relational database model. 2. Evaluate the advantages of the relational database model. 3. Define a database management system and its relationship to a website. 4. Explain why an organization would want to integrate its databases. 7-2 STORING ORGANIZATIONAL INFORMATION • Database management system—Computer program used to manage and query a database • Properties typically considered necessary to constitute a database: – – – – Data are managed to ensure integrity and quality Allows shared access across a community of users Has a schema Supports a query language 7-3 RELATIONAL DATABASE FUNDAMENTALS • Database—Maintains information about various types of objects (inventory), events (transactions), people (employees), and places (warehouses) • Database models include: – Hierarchical Database Model—Information is organized into tree-like structure (using parent/child relationships) in such a way that it cannot have too many relationships – Network Database Model—A flexible way of representing objects and their relationships – Relational Database Model—Stores information in the form of logically related two-dimensional tables 7-4 ENTITIES AND ATTRIBUTES • Entity—A person, place, thing, transaction, or event about which information is stored – The rows in each table contain the entities – In Figure 7.1 CUSTOMER includes Dave’s Sub Shop and Pizza Palace entities • Attributes—Characteristics or properties of an entity class – The columns in each table contain the attributes – In Figure 7.1 attributes for CUSTOMER include Customer ID, Customer Name, Contact Name 7-5 KEYS AND RELATIONSHIPS • Primary Keys and Foreign Keys identify the various entity classes (tables) in the database – Primary Key—A field (or group of fields) that uniquely identifies a given entity in a table – Foreign Key—A primary key of one table that appears as an attribute in another table and acts to provide a logical relationship among the two tables 7-6 RELATIONAL DATABASE ADVANTAGES • Database advantages from a business perspective include: – – – – – Increased flexibility Increased scalability and performance Reduced information redundancy Increased information integrity (quality) Increased information security 7-7 INCREASED FLEXIBILITY • A well-designed database should: 1. Handle changes quickly and easily. 2. Provide users with different views. 3. Have only one physical view. • Physical View—Deals with the physical storage of information on a storage device. 4. Have multiple logical views. • Logical View—Focuses on how users logically access information. 7-8 INCREASED SCALABILITY AND PERFORMANCE • A database must scale to meet increased demand, while maintaining acceptable performance levels – Scalability—Refers to how well a system can adapt to increased demands – Performance—Measures how quickly a system performs a certain process or transaction 7-9 REDUCED INFORMATION REDUNDANCY • Databases reduce information redundancy: – Redundancy—The duplication of information or storing the same information in multiple places • Inconsistency is one of the primary problems with redundant information 7-10 INCREASED INFORMATION INTEGRITY (QUALITY) • Information Integrity—Measures the quality of information • Integrity Constraint—Rules that help ensure the quality of information – Relational Integrity Constraints—Rules that enforce basic and fundamental information-based constraints – Business-Critical Integrity Constraints—Enforce business rules vital to an organization’s success and often require more insight and knowledge than relational integrity constraints 7-11 INCREASED INFORMATION SECURITY • Databases offer several security features including: – Password—Provides authentication of the user – Access Level—Determines who has access to the different types of information – Access Control—Determines types of user access, such as read-only access • Database Management Systems (DBMS)— Software through which users and application programs interact with a database 7-12 DATABASE MANAGEMENT SYSTEMS • Two primary ways a user can interact with a DBMS: – Directly – Indirectly • Data-Driven Websites—An interactive website kept constantly updated and relevant to the needs of its customers through the use of a database 7-13 DATA-DRIVEN WEBSITES • Data-Driven Website Business Advantages: – Development – Content management – Future expandability – Minimizing human error – Cutting production and update costs – More efficient – Improved stability • Data-Driven Business Intelligence—Companies can gain business intelligence by viewing the data access and analyzed from their website 7-14 INTEGRATING INFORMATON AMONG MULTIPLE DATABASES • Integration—Allows separate systems to communicate directly with each other – Forward Integration—Takes information entered into a given system and sends it automatically to all downstream systems and processes – Backward Integration—Takes information entered into a given system and sends it automatically to all upstream systems and processes 7-15