CGS 2545: Database Concepts

CGS 2545: Database Concepts

اسلاید 1: CGS 2545: Database ConceptsFall 2010Chapter 2 – The Database Development ProcessDepartment of Electrical Engineering and Computer ScienceUniversity of Central FloridaInstructor : Dr. Mark Llewellyn markl@cs.ucf.eduHEC 236, 407-823-2790http://www.cs.ucf.edu/courses/cgs2545/fall2010

اسلاید 2: 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

اسلاید 3: Segment from enterprise data model (Pine Valley Furniture Company) [simplified E-R diagram]Enterprise data model describes the high-level entities in an organization and the relationship between these entities

اسلاید 4: Information Systems Architecture (ISA)Conceptual blueprint for organization’s desired information systems structureConsists of:Data (e.g. Enterprise Data Model – simplified ER Diagram)Processes – data flow diagrams, process decomposition, etc.Data Network – topology diagram People – people management using project management tools (Gantt charts, etc.)Events and points in time (when processes are performed)Reasons for events and rules (e.g. decision tables)

اسلاید 5: Information EngineeringA data-oriented methodology to create and maintain information systemsTop-down planning: a generic IS planning methodology for obtaining a broad understanding of the IS needed by the entire organizationFour steps to Top-Down planning:PlanningAnalysisDesignImplementation

اسلاید 6: Information Systems Planning Purpose: align information technology with organization’s business strategiesThree steps:Identify strategic planning factors GoalsCritical success factorsProblem areasIdentify corporate planning objectsOrganizational unitsLocationsBusiness functionsEntity typesDevelop enterprise modelFunctional decompositionEntity-relationship diagramPlanning matrices

اسلاید 7: Identify Strategic Planning Factors Organization goals – what we hope to accomplishCritical success factors – what MUST work in order for us to surviveProblem areas – weaknesses we now have

اسلاید 8: Identify Corporate Planning Objects Organizational units – departmentsOrganizational locationsBusiness functions – groups of business processesEntity types – the things we are trying to model for the databaseInformation systems – application programs

اسلاید 9: Develop Enterprise ModelFunctional decompositionThe process of breaking down the functions of an organization into progressively greater levels of detail.Enterprise data model See page 3 (Figure 2-1, text page 38).Planning matrixes See page 12 (Figure 2-3, text page 42).

اسلاید 10: Example of process decomposition of an order fulfillment function (Pine Valley Furniture)Decomposition -- breaking large tasks into smaller tasks in a hierarchical structure chart

اسلاید 11: Planning MatrixesDescribe relationships between planning objects in the organizationTypes of matrixes:Function-to-data entity: which data are useful to each function.Location-to-function: which function is performed where.Unit-to-function: which function is performed by which unit.IS-to-data entity: how each IS interacts with each data entity.IS-to-business objective: which IS supports each business objective.

اسلاید 12: Example business function-to-data entity matrix Business PlanningX X X XProduct Development X X X XMaterials Management X X X X X XOrder FulfillmentX X X X X X X X XOrder ShipmentX X X X X XSales SummarizationX X X X XProduction Operations X X X X X X XFinance and AccountingX X X X X X X XCustomerProductRaw MaterialOrder Work CenterWork OrderInvoiceEquipmentEmployeeBusinessFunction (users)Data Entity Types

اسلاید 13: Two Approaches to Database and IS DevelopmentSDLCSystem Development Life CycleDetailed, well-planned development processTime-consuming, but comprehensiveLong development cycleRapid PrototypingRapid application development (RAD)Cursory attempt at conceptual data modeling.Define database during development of initial prototypeRepeat implementation and maintenance activities with new prototype versions

اسلاید 14: Systems Development Life Cycle

اسلاید 15: Database Development Activities During The Systems Development Life Cycle

اسلاید 16:

اسلاید 17: Packaged Data ModelsModel components that can be purchased, customized, and assembled into full-scale data modelsAdvantagesReduced development timeHigher model quality and reliabilityTwo types:Universal data modelsIndustry-specific data models

اسلاید 18: The database design process can be divided into six basic steps. Semantic data models are most relevant to only the first three of these steps.1. Requirements Analysis: The first step in designing a database application is to understand what data is to be stored in the database, what applications must be built on top of it, and what operations are most frequent and subject to performance requirements. Often this is an informal process involving discussions with user groups and studying the current environment. Examining existing applications expected to be replaced or complemented by the database system.Database Design

اسلاید 19: 2. Conceptual Database Design: The information gathered in the requirements analysis step is used to develop a high-level description of the data to be stored in the database, along with the constraints that are known to hold on this data. 3. Logical Database Design: A DBMS must be selected to implement the database and to convert the conceptual database design into a database schema within the data model of the chosen DBMS.Database Design (cont.)

اسلاید 20: 4. Schema Refinement: In this step the schemas developed in step 3 above are analyzed for potential problems. It is in this step that the database is normalized. Normalization of a database is based upon some elegant and powerful mathematical theory. We will discuss normalization later in the term.5.  Physical Database Design: At this stage in the design of a database, potential workloads and access patterns are simulated to identify potential weaknesses in the conceptual database. This will often cause the creation of additional indices and/or clustering relations. In critical situations, the entire conceptual model will need restructuring.Database Design (cont.)

اسلاید 21: 6. Security Design: Different user groups are identified and their different roles are analyzed so that access patterns to the data can be defined. There is often a seventh step in this process with the last step being a tuning phase, during which the database is made operational (although it may be through a simulation) and further refinements are made as the system is “tweaked” to provide the expected environment.The illustration on the following page summarizes the main phases of database design.Database Design (cont.)

اسلاید 22: Database Design (cont.)MiniworldRequirements Collection and AnalysisConceptual DesignLogical Design – (data model mapping)Physical Design Database RequirementsConceptual Schema (high-level data model)Logical Schema (data model of specific DBMS)Internal SchemaFunctional RequirementsFunctional AnalysisHigh-level Transaction SpecificationApplication Program DesignTransaction ImplementationApplication ProgramsDBMS-independentDBMS-specific

اسلاید 23: CASEComputer-Aided Software Engineering (CASE) – software tools providing automated support for systems developmentThree database features:Data modeling – entity-relationship diagramsCode generation – SQL code for table creationRepositories – knowledge base of enterprise information

اسلاید 24: Managing ProjectsProject – a 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 commitment – review of systems development project after each development phase with re-justification after each phase

اسلاید 25: Managing Projects: People InvolvedSystems analystsDatabase analystsUsersProgrammersDatabase/data administratorsSystems programmers, network administrators, testers, technical writers

اسلاید 26: Gantt ChartShows time estimates of tasks

اسلاید 27: PERT chart (Program Evaluation and Review Technique)Shows dependencies between task