Database & Information Systems 8 Chapter Database & Information Systems 8.1 Managing Files: Basic Concepts 8.2 Database Management Systems 8.3 Database Models 8.4 Data Mining 8.5 Databases & The Digital Economy 8.6 Using Databases to Help Make Decisions 8.7 Artificial Intelligence 8.8 The Ethics of Using Databases McGraw-Hill/Irwin © 2007 The McGraw-Hill Companies, Inc. All rights reserved.

Managing Files: Basic Concepts A database is a logically organized collection of related data designed and built for a specific purpose Data is stored hierarchically for easier storage and retrieval Files: collections of related records Records: collections of related fields Field: unit of data containing 1 or more characters Character: a letter number or special character made of bits Bit: a 0 or 1

Managing Files: Basic Concepts Key Field – the field that identifies a record Often an identifying number, such as social security number Primary keys must be unique Keys are used to pick records out of a database Unique keys make records stand out from each other If two records had the same key, then you might not pick the correct one Nonprimary keys are used to sort records in different ways Foreign keys are fields that appear in two different tables and are used to relate one table to another

Managing Files: Basic Concepts This example shows a sample database in Microsoft Access. Products is a table. ProductID is the primary key of the Product table. ProductID is also a foreign key in the Orders table

Managing Files: Basic Concepts Program files are files containing software instructions Source program files are written by the software developer in the programming language Double-clicking on them won’t run them They have file extensions like .cpp, .jav, .bas Executable files are program files translated so they can be executed on the computer Double-clicking on them will cause them to run They have file extensions like .exe or .com

Managing Files: Basic Concepts Data files are files that contain data such as words, numbers, pictures, or sounds These are the files that are used in databases They have extensions such as .txt .mdb, and .xls Graphics files have extensions like .tiff, .jpeg, and .png Audio files have extensions such as .mp3, .wav, and .mid Animation/video files have extensions such as .qt, .mpg, .avi, and .rm Data files are often compressed to save space and transmit them faster Compression removes repetitive elements from a file

Database Management Systems Software written specifically to control the structure of a database and access to the data Reduced data redundancy Redundant data is stored in multiple places, which causes problems keeping all the copies current Improved data integrity Means the data is accurate, consistent, and up to date Increased security Limits who can create, read, update, and delete the data Ease of data maintenance Offer validation checks, backup utilities, and procedures for data inserting, updating, and deletion

Database Management Systems 3 Principal Components Data Dictionary A repository that stores the data definitions and descriptions of the structure of the data and the database DBMS Utilities Programs that allow you to maintain the database by creating, editing, deleting data, records, and files Also include automated backup and recovery Report Generator Program for producing an on-screen or printed document form all or part of a database

Database Management Systems Database Administrator Database Administrator (DBA) A high-paid, responsible position within an organization Coordinates all related activities and needs for an organization’s database Ensures the database’s Recoverability Integrity Security Availability Reliability Performance Discussion Question: Did you know that 93% of companies that lost their data center for 10 days or more due to a disaster filed for bankruptcy within a year?

Database Models Hierarchical database Network database Relational database Object-oriented database Multidimensional database Fields or records are arranged in a family tree, with child records subordinate to parent or higher-level records Like a hierarchical database, but each child record can have more than one parent record Relates, or connects, data in different files through the use of a key, or common data element Uses objects (software written in small, reusable chunks) as elements within database files Models data as facts, dimensions, or numerical measures for use in the interactive analysis of large amounts of data

Database Models Hierarchical Databases Fields or records are arranged in related groups resembling a family tree with child (low-level) records subordinate to parent (high-level) records Root record is the parent record at the top of the database, and data is accessed through the hierarchy Oldest and simplest; used in mainframes

Database Models Network Database Similar to a hierarchical database, but each child record can have more than one parent record Used principally with mainframe computers Requires the database structure to be defined in advance

Database Models Relational Database Relates or connects data in different files through the use of a key, or common data element Examples are Oracle, Informix, Sybase Data exists independently of how it is physically stored Users don’t need to know data structure to use the database Uses SQL (structured query language) to create, modify, maintain, and query the data Query by Example uses sample records or forms to allow users to define the qualifications for choosing records

Database Models Object-oriented Databases Use “objects”, software written in small, manageable chunks, as elements within data files An object consists of Data in any form, including audio, graphics, and video Instructions on the action to be taken with the data Examples include FastObjects, GemStone, Objectivity DB, Jasmine Object Database, and KE Express Types include Web database Hypermedia database

Database Models Multidimensional Database Models data as facts, dimensions, or numerical answers for use in the interactive analysis of large amounts of data for decision-making purposes Allows users to ask questions in colloquial English Use OLAP (Online Analytical Processing) software to provide answers to complex database queries