© 2005 by Prentice Hall 1 Chapter 1: The Database Environment Modern Database Management 7 th Edition Jeffrey A. Hoffer, Mary B. Prescott, Fred R. McFadden.

© 2005 by Prentice Hall© 2005 by Prentice Hall 11

Chapter 1:Chapter 1:The Database The Database EnvironmentEnvironment

Modern Database Modern Database ManagementManagement

77thth Edition EditionJeffrey A. Hoffer, Mary B. Prescott, Jeffrey A. Hoffer, Mary B. Prescott,

Fred R. McFaddenFred R. McFadden

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ObjectivesObjectives Definition of termsDefinition of terms Explain growth and importance of databasesExplain growth and importance of databases Name limitations of conventional file Name limitations of conventional file

processingprocessing Identify categories of databasesIdentify categories of databases Explain advantages of databasesExplain advantages of databases Identify costs and risks of databasesIdentify costs and risks of databases List components of database environmentList components of database environment Describe evolution of database systemsDescribe evolution of database systems

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DefinitionsDefinitions Database: organized collection of logically Database: organized collection of logically

related datarelated data Data: stored representations of meaningful Data: stored representations of meaningful

objects and eventsobjects and events Structured: numbers, text, datesStructured: numbers, text, dates Unstructured: images, video, documentsUnstructured: images, video, documents

Information: data processed to increase Information: data processed to increase knowledge in the person using the dataknowledge in the person using the data

Metadata: data that describes the properties Metadata: data that describes the properties and context of user dataand context 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 useful information that managers can use for decision making and

interpretation

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

data context

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Disadvantages of File Disadvantages of File ProcessingProcessing

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

Duplication of DataDuplication of Data Different systems/programs have separate copies of the Different systems/programs have separate copies of the

same datasame data

Limited Data SharingLimited Data Sharing No centralized control of dataNo centralized control of data

Lengthy Development TimesLengthy Development Times Programmers must design their own file formatsProgrammers must design their own file formats

Excessive Program MaintenanceExcessive Program Maintenance 80% of of information systems budget80% of of information systems budget

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Problems with Data Problems with Data DependencyDependency

Each application programmer must Each application programmer must maintain their own datamaintain their own data

Each application program needs to Each application program needs to include code for the metadata of each include code for the metadata of each filefile

Each application program must have its Each application program must have its own processing routines for reading, own processing routines for reading, inserting, updating and deleting datainserting, updating and deleting data

Lack of coordination and central controlLack of coordination and central control Non-standard file formatsNon-standard file formats

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Figure 1-2 Three file processing systems at Pine Valley Furniture

Duplicate Data

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Problems with Data Problems with Data RedundancyRedundancy

Waste of space to have duplicate dataWaste of space to have duplicate data Causes more maintenance headachesCauses more maintenance headaches The biggest problem: The biggest problem:

When data changes in one file, When data changes in one file, could cause inconsistenciescould cause inconsistencies

Compromises Compromises data integritydata integrity

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SOLUTION: SOLUTION: The DATABASE ApproachThe DATABASE Approach

Central repository of shared dataCentral repository of shared data Data is managed by a controlling Data is managed by a controlling

agentagent Stored in a standardized, Stored in a standardized,

convenient formconvenient form

Requires a Database Management System (DBMS)

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Database Management Database Management SystemSystem

DBMS manages data resources like an operating system manages hardware resources

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

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Elements of the Database Elements of the Database ApproachApproach

Enterprise Data ModelEnterprise Data Model Graphical model showing high-level entities and Graphical model showing high-level entities and

relationships for the organizationrelationships for the organization Relational DatabasesRelational Databases

Database technology involving tables (relations) Database technology involving tables (relations) representing entities and primary/foreign keys representing representing entities and primary/foreign keys representing relationshipsrelationships

Use of Internet TechnologyUse of Internet Technology Networks and telecommunications, distributed databases, Networks and telecommunications, distributed databases,

client-server and 3-tier architecturesclient-server and 3-tier architectures Database ApplicationsDatabase Applications

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

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One customer may place many orders, but each order is placed by a single customer

One-to-many relationship

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One order has many order lines; each order line is associated with a single order

One-to-many relationship

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One product can be in many order lines, each order line refers to a single product

One-to-many relationship

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Therefore, one order involves many products and one product is involved in many orders

Many-to-many relationship

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Relationships established in special columns that provide links between tables

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Client/server system architecture

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Application program functions: inserting new data, updating existing data, deleting existing data, reading data for display

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Figure 1-9 Workgroup database with local area network

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Figure 1-10 An enterprise data warehouse

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Components of the Components of the Database EnvironmentDatabase Environment

CASE ToolsCASE Tools – computer-aided software engineering – computer-aided software engineering RepositoryRepository – centralized storehouse of metadata – centralized storehouse of metadata Database Management System (DBMS)Database Management System (DBMS) – software for – software for

managing the databasemanaging the database DatabaseDatabase – storehouse of the data – storehouse of the data Application ProgramsApplication Programs – software using the data – software using the data User InterfaceUser Interface – text and graphical displays to users – text and graphical displays to users Data AdministratorsData Administrators – personnel responsible for – personnel responsible for

maintaining the databasemaintaining the database System DevelopersSystem Developers – personnel responsible for designing – personnel responsible for designing

databases and softwaredatabases and software End UsersEnd Users – people who use the applications and databases – people who use the applications and databases

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Figure 1-11 Components of the database environment

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Evolution of DB SystemsEvolution of DB Systems

Flat files - 1960s - 1980sFlat files - 1960s - 1980s Hierarchical – 1970s - 1990sHierarchical – 1970s - 1990s Network – 1970s - 1990sNetwork – 1970s - 1990s Relational – 1980s - presentRelational – 1980s - present Object-oriented – 1990s - presentObject-oriented – 1990s - present Object-relational – 1990s - presentObject-relational – 1990s - present Data warehousing – 1980s - presentData warehousing – 1980s - present Web-enabled – 1990s - presentWeb-enabled – 1990s - present