Chapter 2:Chapter 2: The Database The Database

Development Process Development Process

Modern Database Modern Database ManagementManagement

99thth Edition EditionJeffrey A. Hoffer, Mary B. Prescott, Jeffrey A. Hoffer, Mary B. Prescott,

Heikki Topi Heikki Topi

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Enterprise Data ModelEnterprise Data Model

First step in database developmentFirst step in database development Specifies scope and general contentSpecifies scope and general content Overall picture of organizational data at Overall picture of organizational data at

high level of abstractionhigh level of abstraction Entity-relationship diagramEntity-relationship diagram Descriptions of entity typesDescriptions of entity types Relationships between entitiesRelationships between entities Business rulesBusiness rules

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Segment from enterprise data model

Enterprise data model describes the high-level entities in an organization and the relationship between these entities

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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

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Systems Development Life CycleSystems Development Life Cycle

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Planning

Analysis

Physical Design

Implementation

Maintenance

Logical Design

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Systems Development Life CycleSystems Development Life Cycle (cont.) (cont.)

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Planning

Analysis

Physical Design

Implementation

Maintenance

Logical Design

Planning Purpose––preliminary understandingDeliverable––request for study

Database activity–– enterprise modeling and early conceptual data modeling

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Systems Development Life CycleSystems Development Life Cycle (cont.) (cont.)

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Planning

Analysis

Physical Design

Implementation

Maintenance

Logical Design

Analysis

Purpose–thorough requirements analysis and structuringDeliverable–functional system specifications

Database activity–thorough and integrated conceptual data modeling

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Systems Development Life CycleSystems Development Life Cycle (cont.) (cont.)

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Planning

Analysis

Physical Design

Implementation

Maintenance

Logical DesignLogical Design

Purpose–information requirements elicitation and structureDeliverable–detailed design specifications

Database activity– logical database design (transactions, forms, displays, views, data integrity and security)

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Systems Development Life CycleSystems Development Life Cycle (cont.) (cont.)

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Planning

Analysis

Physical Design

Implementation

Maintenance

Logical Design

Physical Design

Purpose–develop technology and organizational specificationsDeliverable–program/data structures, technology purchases, organization redesigns

Database activity– physical database design (define database to DBMS, physical data organization, database processing programs)

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Systems Development Life CycleSystems Development Life Cycle (cont.) (cont.)

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Planning

Analysis

Physical Design

Implementation

Maintenance

Logical Design

Implementation

Purpose–programming, testing, training, installation, documentingDeliverable–operational programs, documentation, training materials

Database activity– database implementation, including coded programs, documentation, installation and conversion

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Systems Development Life CycleSystems Development Life Cycle

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Planning

Analysis

Physical Design

Implementation

Maintenance

Logical Design

Maintenance

Purpose–monitor, repair, enhanceDeliverable–periodic audits

Database activity– database maintenance, performance analysis and tuning, error corrections

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Prototyping Database Prototyping Database MethodologyMethodology

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Prototyping Database Prototyping Database MethodologyMethodology

(cont.)(cont.)

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Prototyping Database Prototyping Database MethodologyMethodology

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Prototyping Database Prototyping Database MethodologyMethodology

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Prototyping Database Prototyping Database MethodologyMethodology

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Packaged Data ModelsPackaged Data Models

Model components that can be purchased, Model components that can be purchased, customized, and assembled into full-scale customized, and assembled into full-scale data modelsdata models

AdvantagesAdvantages Reduced development timeReduced development time Higher model quality and reliabilityHigher model quality and reliability

Two types:Two types: Universal data modelsUniversal data models Industry-specific data modelsIndustry-specific data models

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Managing ProjectsManaging Projects Project–a planned undertaking of related

activities to reach an objective that has a reach an objective that has a beginning and an endbeginning and an end

Involves use of review points for:Involves use of review points for: Validation of satisfactory progressValidation of satisfactory progress Step back from detail to overall viewStep back from detail to overall view Renew commitment of stakeholdersRenew commitment of stakeholders

Incremental commitment–review of systems Incremental commitment–review of systems development project after each development development project after each development phase with re justification after each phasephase with re justification after each phase

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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

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Database SchemaDatabase Schema• Internal level: describes how data is : describes how data is

stored. The way perceived by the DBMS & stored. The way perceived by the DBMS & OS.OS.

• Conceptual levelConceptual level: describes what data : describes what data stored in DB, and the relationships stored in DB, and the relationships among the data. The way perceived by among the data. The way perceived by the DBA & programmers.the DBA & programmers.

• External levelExternal level: describes the part of : describes the part of the DB that user is interested in. The way the DB that user is interested in. The way perceived by the end users.perceived by the end users.

2020Database Systems: A Practical Approach to Design, Implementation and Management, by

T. Connolly and C. Begg.

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

The internal schema is the underlying design and implementation

Three-schema architecture

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