2011 Pearson Education, Inc. Publishing as Prentice Hall*Chapter 1:The Database Environment and Development ProcessModern Database Management10th EditionJeffrey A. Hoffer, V. Ramesh, Heikki Topi

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*ObjectivesDefine termsName limitations of conventional file processingExplain advantages of databasesIdentify costs and risks of databasesList components of database environmentIdentify categories of database applicationsDescribe database system development life cycleExplain prototyping and agile development approachesExplain roles of individualsExplain the three-schema architecture for databases

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*DefinitionsDatabase: organized collection of logically related dataData: stored representations of meaningful objects and eventsStructured: numbers, text, datesUnstructured: images, video, documentsInformation: data processed to increase knowledge in the person using the dataMetadata: data that describes the properties and context of user data

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*Figure 1-1a Data in contextContext helps users understand data

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*Graphical displays turn data into useful information that managers can use for decision making and interpretationFigure 1-1b Summarized data

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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 ProcessingProgram-Data DependenceAll programs maintain metadata for each file they useDuplication of DataDifferent systems/programs have separate copies of the same dataLimited Data SharingNo centralized control of dataLengthy Development TimesProgrammers must design their own file formatsExcessive Program Maintenance80% of information systems budget

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*Problems with Data DependencyEach application programmer must maintain his/her own dataEach application program needs to include code for the metadata of each fileEach application program must have its own processing routines for reading, inserting, updating, and deleting dataLack of coordination and central controlNon-standard file formats

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*Problems with Data RedundancyWaste of space to have duplicate dataCauses 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 dataData is managed by a controlling agentStored in a standardized, convenient form

Requires a Database Management System (DBMS)

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*Database Management SystemDBMS manages data resources like an operating system manages hardware resourcesA software system that is used to create, maintain, and provide controlled access to user databasesOrder Filing SystemInvoicing SystemPayroll SystemDBMS

Central database

Contains employee,order, inventory, pricing, and customer data

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*Advantages of the Database ApproachProgram-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 ApproachNew, specialized personnelInstallation and management cost and complexityConversion costsNeed for explicit backup and recoveryOrganizational conflict

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*Elements of the Database ApproachData models Graphical system capturing nature and relationship of dataEnterprise Data Modelhigh-level entities and relationships for the organizationProject Data Modelmore detailed view, matching data structure in database or data warehouse EntitiesNoun form describing a person, place, object, event, or conceptComposed of attributesRelationshipsBetween entitiesUsually one-to-many (1:M) or many-to-many (M:N)Relational DatabasesDatabase technology involving tables (relations) representing entities and primary/foreign keys representing relationships

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*Segment of an enterprise data modelSegment of a project-level data modelFigure 1-3 Comparison of enterprise and project level data models

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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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*Figure 1-5 Components of the Database Environment

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*Components of the Database EnvironmentCASE Toolscomputer-aided software engineeringRepositorycentralized storehouse of metadataDatabase Management System (DBMS) software for managing the databaseDatabasestorehouse of the dataApplication Programssoftware using the dataUser Interfacetext and graphical displays to usersData/Database Administratorspersonnel responsible for maintaining the databaseSystem Developerspersonnel responsible for designing databases and softwareEnd Userspeople who use the applications and databases

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*The Range of Database ApplicationsPersonal databasesTwo-tier Client/Server databasesMultitier Client/Server databasesEnterprise applicationsEnterprise resource planning (ERP) systemsData warehousing implementations

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*Figure 1-6 Two-tier database with localarea network

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*Figure 1-7 Three-tiered client/server database architecture

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*Enterprise Database ApplicationsEnterprise Resource Planning (ERP)Integrate all enterprise functions (manufacturing, finance, sales, marketing, inventory, accounting, human resources)Data WarehouseIntegrated decision support system derived from various operational databases

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*Figure 1-8a Evolution of database technologies

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*Enterprise Data ModelFirst step in database developmentSpecifies scope and general contentOverall picture of organizational data at high level of abstractionEntity-relationship diagramDescriptions of entity typesRelationships between entitiesBusiness rules

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*FIGURE 1-9 Example business function-to-data entity matrix

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*Two Approaches to Database and IS DevelopmentSDLCSystem Development Life CycleDetailed, well-planned development processTime-consuming, but comprehensiveLong development cyclePrototypingRapid application development (RAD)Cursory attempt at conceptual data modelingDefine database during development of initial prototypeRepeat implementation and maintenance activities with new prototype versions

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*Systems Development Life Cycle(see also Figure 1-10)

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*Systems Development Life Cycle(see also Figure 1-10) (cont.)PlanningPurposepreliminary understandingDeliverablerequest for study Database activity enterprise modeling and early conceptual data modeling

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*Systems Development Life Cycle(see also Figure 1-10) (cont.) AnalysisPurposethorough requirements analysis and structuringDeliverablefunctional system specificationsDatabase activitythorough and integrated conceptual data modeling

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*Systems Development Life Cycle(see also Figure 1-10) (cont.) Logical DesignPurposeinformation requirements elicitation and structureDeliverabledetailed design specificationsDatabase activity logical database design (transactions, forms, displays, views, data integrity and security)

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*Systems Development Life Cycle(see also Figure 1-10) (cont.) Physical DesignPurposedevelop technology and organizational specifications

Deliverableprogram/data structures, technology purchases, organization redesignsDatabase activity physical database design (define database to DBMS, physical data organization, database processing programs)

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*Systems Development Life Cycle(see also Figure 1-10) (cont.) ImplementationPurposeprogramming, testing, training, installation, documenting

Deliverableoperational programs, documentation, training materialsDatabase activity database implementation, including coded programs, documentation, installation and conversion

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*Systems Development Life Cycle(see also Figure 1-10) (cont.) MaintenancePurposemonitor, repair, enhance

Deliverableperiodic auditsDatabase activity database maintenance, performance analysis and tuning, error corrections

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*Prototyping Database Methodology (Figure 1-11)

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*Prototyping Database Methodology (Figure 1-11) (cont.)

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*Prototyping Database Methodology (Figure 1-11) (cont.)

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*Prototyping Database Methodology (Figure 1-11) (cont.)

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*Prototyping Database Methodology (Figure 1-11) (cont.)

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*Database SchemaExternal SchemaUser ViewsSubsets of Conceptual SchemaCan be determined from business-function/data entity matricesDBA determines schema for different usersConceptual SchemaE-R modelscovered in Chapters 2 and 3Internal Schema Logical structurescovered in Chapter 4Physical structurescovered in Chapter 5

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*Different people have different views of the databasethese are the external schemaThe internal schema is the underlying design and implementationFigure 1-12 Three-schema architecture

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*Managing ProjectsProjecta planned undertaking of related activities to reach an objective that has a beginning and an endInvolves use of review points for:Validation of satisfactory progressStep back from detail to overall viewRenew commitment of stakeholdersIncremental commitmentreview of systems development project after each development phase with rejustification after each phase

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*Managing Projects: People InvolvedBusiness analystsSystems analystsDatabase analysts and data modelersUsersProgrammersDatabase architectsData administratorsProject managersOther technical experts

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*FIGURE 1-13 ComputerSystem for Pine ValleyFurniture Company

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