© Prentice Hall 1 Chapter 1: The Database Environment

© Prentice Hall© Prentice Hall 11

Chapter 1:Chapter 1:

The Database The Database EnvironmentEnvironment

22Chapter 1 & 2 © Prentice Hall© Prentice Hall

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 five categories of databasesIdentify five 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


DefinitionsDefinitions 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

Database: organized collection of logically Database: organized collection of logically related datarelated data

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


Systems and Systems and ProceduresProcedures

Product flow and information flowProduct flow and information flow Product flow: the flow of raw materials into Product flow: the flow of raw materials into

assemblies and finally into finished goods.assemblies and finally into finished goods. Information flow: the creation of movement Information flow: the creation of movement

of the administrative and operational of the administrative and operational documentation necessary for product flow.documentation necessary for product flow.


Product flow and Information Product flow and Information flowflow

Customers Employees

Collection (8)

Sales(5)

Production(4)

Distribution(6)

Inventory(3)

Receiving(2)

Paying(9)

Purchasing(1)

VendorsBilling

(7)

Data to Information flow is as if raw material to production flow.


The evolution of product flow The evolution of product flow and information flowand information flow

data processing information

raw materials

productionfinishedgoods

Input Output

furtherprocessing

??

technicalsupport

??


Figure 1-1a Data in context

Context helps users understand data


Graphical displays turn data into useful information that managers can use for decision making and

interpretation

Figure 1-1b Summarized data


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

data context


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 information systems budget80% of information systems budget


Figure 1-3 Old file processing systems at Pine Valley Furniture Company

Duplicate Data


Problems with Program Data Problems with Program Data DependencyDependency

Each application programmer must Each application programmer must maintain his/her own datamaintain his/her 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 own processing routines for database database operationsoperations: reading, inserting, updating, : reading, inserting, updating, and deleting dataand deleting data

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


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:

Data changes in one file could cause Data changes in one file could cause inconsistenciesinconsistencies

Compromises in Compromises in data integritydata integrity


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)


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

Order Filing System

Invoicing System

Payroll System

DBMSCentral database

Contains employee,order, inventory,

pricing, and customer data


Advantages of the Database Advantages of the Database ApproachApproach

Program-data independence (PI)Program-data independence (PI) Planned (minimal) data redundancy (DR)Planned (minimal) data redundancy (DR) Improved data consistencyImproved data consistency Improved data sharingImproved data sharing Increased application development Increased application development

productivityproductivity Enforcement of standardsEnforcement of standards Improved data qualityImproved data quality Improved data accessibility and Improved data accessibility and

responsivenessresponsiveness Reduced program maintenanceReduced program maintenance Improved decision supportImproved decision support


Costs and Risks of the Database Costs and Risks of the Database ApproachApproach

New, specialized personnelNew, specialized personnel Installation and management cost Installation and management cost

and complexityand complexity Conversion costsConversion costs Need for explicit backup and Need for explicit backup and

recoveryrecovery Organizational conflictOrganizational conflict


Figure 2-9 Three-tiered client/server database architecture

Data tier

Presentation tier

Business logic tier


Evolution of DB SystemsEvolution of DB Systems

© Prentice Hall© Prentice Hall 2020

Chapter 2:Chapter 2:

The Database The Database Development Process Development Process


ObjectivesObjectives Definition of termsDefinition of terms Describe system development life cycleDescribe system development life cycle Explain prototyping approachExplain prototyping approach Explain roles of individualsExplain roles of individuals Explain three-schema approachExplain three-schema approach Explain role of packaged data modelsExplain role of packaged data models Explain three-tiered architecturesExplain three-tiered architectures Explain scope of database design projectsExplain scope of database design projects Draw simple data modelsDraw simple data models


Information Systems Information Systems ArchitectureArchitecture

(ISA)(ISA) Conceptual blueprint for organization’s Conceptual blueprint for organization’s

desired information systems structuredesired information systems structure Consists of (Consists of (6Ws6Ws):):

ProcessesProcesses––data flow diagrams, process data flow diagrams, process decomposition, etc. (DFD- Data Flow Diagram)decomposition, etc. (DFD- Data Flow Diagram)

Data (e.g. Enterprise Data ModelData (e.g. Enterprise Data Model––ER Diagram)ER Diagram) Data NetworkData Network––topology diagram (like Fig 1-9)topology diagram (like Fig 1-9) PeoplePeople––people management using project people management using project

management tools (Gantt charts, etc.)management tools (Gantt charts, etc.) Events and points in time (when processes are Events and points in time (when processes are

performed. Use case diagram)performed. Use case diagram) Reasons for events and rules (e.g., decision Reasons for events and rules (e.g., decision

tables)tables)

WhatWhat

HowHow

WhereWhere

WhoWho

WhenWhen

WhyWhy


Data Flow DiagramsData Flow Diagrams Data flow diagrams (DFDs) are Data flow diagrams (DFDs) are

graphical aids that describe an graphical aids that describe an information systeminformation system

Advantages:Advantages: freedom from committing to the technical freedom from committing to the technical

implementation of the system too early.implementation of the system too early. Further understanding the Further understanding the

interrelatedness of systems and interrelatedness of systems and subsystems.subsystems.

communicating current system communicating current system knowledge to users .knowledge to users .


Data Flow DiagramsData Flow Diagrams

Data flow diagram symbolsData flow diagram symbols Four basic symbolsFour basic symbols

ProcessProcess

Data flowData flow

Data storeData store

External entityExternal entity


Process

Data flowsExternal entities


Data store




Figure 2-2 Example of process decomposition of an order fulfillment function (Pine Valley Furniture)

Decomposition = breaking large tasks into smaller tasks in a hierarchical structure chart

Order form Credit status


Information Systems Information Systems ArchitectureArchitecture

(ISA)(ISA) Conceptual blueprint for organization’s Conceptual blueprint for organization’s

desired information systems structuredesired information systems structure Consists of (Consists of (6Ws6Ws):):

ProcessesProcesses––data flow diagrams, process data flow diagrams, process decomposition, etc. (DFD- Data Flow Diagram)decomposition, etc. (DFD- Data Flow Diagram)

Data (e.g. Enterprise Data ModelData (e.g. Enterprise Data Model––ER Diagram)ER Diagram) Data NetworkData Network––topology diagram (like Fig 1-9)topology diagram (like Fig 1-9) PeoplePeople––people management using project people management using project

management tools (Gantt charts, etc.)management tools (Gantt charts, etc.) Events and points in time (when processes are Events and points in time (when processes are

performed. Use case diagram)performed. Use case diagram) Reasons for events and rules (e.g., decision Reasons for events and rules (e.g., decision

tables)tables)

WhatWhat

HowHow

WhereWhere

WhoWho

WhenWhen

WhyWhy


Develop Enterprise ModelDevelop Enterprise Model

Process: Data flow diagram (DFD)Process: Data flow diagram (DFD)

Functional decompositionFunctional decompositionIterative process breaking system description into finer and finer detail

Data: Entity Relationship diagram (ER Diagram)Data: Entity Relationship diagram (ER Diagram)

Planning matrixes Planning matrixes Describe interrelationships between planning objects


Data DictionaryData Dictionary

DataEntity (table)

ProgramModules

DataEntity (table)

DataElement (field)

Data Modeling using ERD


Example business function-Example business function-to-data entity matrix (Fig. 2-to-data entity matrix (Fig. 2-

3)3)Higherpriority

Spot missing entity


Planning MatrixesPlanning Matrixes Describe relationships between Describe relationships between

planning objects in the organizationplanning objects in the organization Types of matrixes:Types of matrixes:

Function-to-data entityFunction-to-data entity Location-to-functionLocation-to-function Unit-to-functionUnit-to-function IS-to-data entityIS-to-data entity Supporting function-to-data entitySupporting function-to-data entity IS-to-business objectiveIS-to-business objective


Database SchemaDatabase Schema Conceptual SchemaConceptual Schema

E-R models–covered in Chapters 3 and 4E-R models–covered in Chapters 3 and 4 External SchemaExternal Schema

User Views: schema for different usersUser Views: schema for different users Subsets of Conceptual SchemaSubsets of Conceptual Schema Can be determined from Can be determined from

business-function/data entity matricesbusiness-function/data entity matrices Physical Schema (Internal Schema)Physical Schema (Internal Schema)

Physical structures–covered in Chapters 5 Physical structures–covered in Chapters 5 and 6and 6


Different people have different views of the database…these are the external schema

The internal schema is the underlying design and implementation

Figure 2-7 Three-schema architecture


Figure 2-8 Developing the three-tiered architecture


Information EngineeringInformation Engineering Top-down planning–a generic IS Top-down planning–a generic IS

planning methodology for obtaining a planning methodology for obtaining a broad understanding of the IS needed broad understanding of the IS needed by the entire organizationby the entire organization

Four steps to Top-Down planning:Four steps to Top-Down planning: PlanningPlanning AnalysisAnalysis DesignDesign ImplementationImplementation


Two Approaches to Two Approaches to Database and IS Database and IS

DevelopmentDevelopment SDLCSDLC System Development Life CycleSystem Development Life Cycle Detailed, well-planned development processDetailed, well-planned development process Time-consuming, but comprehensiveTime-consuming, but comprehensive Long development cycleLong development cycle

PrototypingPrototyping Rapid application development (RAD)Rapid application development (RAD) Cursory attempt at conceptual data modelingCursory attempt at conceptual data modeling Define database during development of initial prototypeDefine database during development of initial prototype Repeat implementation and maintenance activities with Repeat implementation and maintenance activities with

new prototype versionsnew prototype versions


Systems Development Life CycleSystems Development Life Cycle(see also Figures 2.4, 2.5) (see also Figures 2.4, 2.5)

Planning

Analysis

Physical Design

Implementation

Maintenance

Logical Design


Systems planning Purpose – identify problem’s nature/scope Systems request – begins the process &

describes desired changes/improvements Systems planning – includes preliminary

investigation or feasibility study End product – preliminary investigation report

Systems Development Life Cycle


Systems analysis Purpose is to learn exactly how the current

system operates or determine what systems should do.

Fact-finding or requirements determination is used to define all functions of the current system



Options Develop a system in-house Purchase a commercial package Modify an existing system Stop development

The end product for this phase is the systems requirements document



Systems design Purpose is to satisfy all documented requirements identify what and how the system must do. Identify all outputs, inputs, files, manual procedures, &

application programs user interface design, files organization and database

design Avoid misunderstanding through manager and user

involvement End product is system design specification



Systems implementationConstruct/deliver information system Prepares functioning, documented systemWrite, test, document application programsUser and manager approval obtainedFile conversion occursUsers, managers, IS staff trained to operate and

support the systemPost-implementation evaluation performed



Prototyping Database Prototyping Database MethodologyMethodology(Figure 2.6) (Figure 2.6)


Prototyping Database Prototyping Database MethodologyMethodology

(Figure 2.6) (Figure 2.6) (cont.)(cont.)



(Figure 2.6)(Figure 2.6) (cont.) (cont.)



(Figure 2.6)(Figure 2.6) (cont.) (cont.)



(Figure 2.6) (Figure 2.6) (cont.)(cont.)


CASECASE Computer-Aided Software Engineering Computer-Aided Software Engineering

(CASE)–software tools providing automated (CASE)–software tools providing automated support for systems developmentsupport for systems development

Three database features:Three database features: Data modeling–drawing entity-relationship Data modeling–drawing entity-relationship

diagramsdiagrams Code generation–SQL code for table creationCode generation–SQL code for table creation Repositories–knowledge base of enterprise Repositories–knowledge base of enterprise

informationinformation


Managing Projects: People Managing Projects: People InvolvedInvolved

Business analystsBusiness analysts Systems analystsSystems analysts Database analysts and data modelersDatabase analysts and data modelers UsersUsers ProgrammersProgrammers Database architectsDatabase architects Data administratorsData administrators Project managersProject managers Other technical expertsOther technical experts


Figure 1-5 Components of the Database Environment

Documents

© Prentice Hall 1 Chapter 1: The Database Environment