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Chapter 1The Database Environment

Modern Database Management8 th Edition

Jeffrey A. Hoffer, Mary B. Prescott,Fred R. McFadden


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Chapter 1 2007 by Prentice Hall 2

ObjectivesDefinition of termsExplain growth and importance of databasesName limitations of conventional file processingIdentify five categories of databasesExplain advantages of databasesIdentify costs and risks of databasesList components of database environmentDescribe evolution of database systems


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DefinitionsDatabase: organized collection of logicallyrelated dataData: stored representations of meaningfulobjects and events

Structured: numbers, text, datesUnstructured: images, video, documents

Information: data processed to increaseknowledge in the person using the data

Metadata: data that describes the properties andcontext of user data


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Figure 1-1a Data in context

Context helps users understand data


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Graphical displays turn data into usefulinformation that managers can use for

decision making and interpretation

Figure 1-1b Summarized data


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Descriptions of the properties or characteristics of thedata, including data types, field sizes, allowable

values, and data context


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Disadvantages of File Processing

Program-Data Dependence All programs maintain metadata for each file they use

Duplication of DataDifferent systems/programs have separate copies of the same data

Limited Data SharingNo centralized control of data

Lengthy Development Times

Programmers must design their own file formatsExcessive Program Maintenance

80% of information systems budget


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Problems with Data DependencyEach application programmer must maintainhis/her own dataEach application program needs to includecode for the metadata of each fileEach application program must have its ownprocessing routines for reading, inserting,updating, and deleting data

Lack of coordination and central controlNon-standard file formats


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Figure 1-3 Old file processing systems at Pine ValleyFurniture Company

Duplicate Data


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Problems with Data Redundancy

Waste of space to have duplicate data

Causes more maintenance headachesThe biggest problem:

Data changes in one file could cause

inconsistenciesCompromises in data integrity


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SOLUTION:

The DATABASE ApproachCentral repository of shared data

Data is managed by a controllingagentStored in a standardized, convenient

formRequires a Database Management System (DBMS)


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Database Management System

DBMS manages data resources like an operating system manages hardware resources

A software system that is used to create, maintain, and providecontrolled access to user databases

Order FilingSystem

InvoicingSystem

PayrollSystem

DBMSCentral database

Contains employee,order, inventory,

pricing, and

customer data


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Advantages of the Database Approach

Program-data independencePlanned data redundancyImproved data consistencyImproved data sharingIncreased application development productivityEnforcement of standardsImproved data qualityImproved data accessibility and responsivenessReduced program maintenanceImproved decision support


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Costs and Risks of the Database Approach

New, specialized personnelInstallation and management cost and

complexityConversion costsNeed for explicit backup and recoveryOrganizational conflict


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Elements of the Database Approach

Data modelsGraphical system capturing nature and relationship of dataEnterprise Data Model high-level entities and relationships forthe organizationProject Data Model more detailed view, matching data structurein database or data warehouse

Relational DatabasesDatabase technology involving tables (relations) representingentities and primary/foreign keys representing relationships

Use of Internet TechnologyNetworks and telecommunications, distributed databases, client-server, and 3-tier architectures

Database Applications Application programs used to perform database activities(create, read, update, and delete) for database users


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Segment of an Enterprise Data Model

Segment of a Project-Level Data Model


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One customermay place manyorders, but eachorder is placed bya single customer

One-to-manyrelationship


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One order hasmany order lines;each order line isassociated with asingle order



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One product can be in manyorder lines, eachorder line refersto a single

product



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Therefore, oneorder involvesmany products

and one product isinvolved in manyorders

Many-to-manyrelationship


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Figure 1-4 Enterprise data model for Figure 1-3 segments


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Figure 1-5 Components of the Database Environment


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Components of theDatabase Environment

CASE Tools computer-aided software engineeringRepository centralized storehouse of metadataDatabase Management System (DBMS) softwarefor managing the database

Database storehouse of the data Application Programs software using the dataUser Interface text and graphical displays to usersData/Database Administrators personnel

responsible for maintaining the databaseSystem Developers personnel responsible fordesigning databases and softwareEnd Users people who use the applications anddatabases


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The Range of Database Applications

Personal databasesWorkgroup databases

Departmental/divisional databasesEnterprise databaseWeb-Enabled database


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Figure 1-6Typical datafrom apersonaldatabase


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Figure 1-7 Workgroup database with wirelesslocal area network


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Enterprise Database Applications

Enterprise Resource Planning (ERP)Integrate all enterprise functions

(manufacturing, finance, sales, marketing,inventory, accounting, human resources)

Data WarehouseIntegrated decision support system derivedfrom various operational databases


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Figure 1-8 An enterprise data warehouse


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Evolution of DB Systems

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