964 database development process intro1

Chapter 2: The Database Development Process Modern Database Management 7 th Edition Jeffrey A. Hoffer, Mary B. Prescott, Fred R. McFadden

Objectives Definition of terms Describe system development life cycle Explain prototyping approach Explain roles of individuals Explain three-schema approach Explain role of packaged data models Explain three-tiered architectures Draw simple data models

Enterprise Data Model First step in database development Specifies scope and general content Overall picture of organizational data at high level of abstraction Entity-relationship diagram Descriptions of entity types Relationships between entities Business rules

Figure 2-1 Segment from enterprise data model (Pine Valley Furniture Company) [simplified E-R diagram, repeat of figure 1.3] Enterprise data model describes the high-level entities in an organization and the relationship between these entities

Information Systems Architecture (ISA) Conceptual blueprint for organization’s desired information systems structure Consists of: Data (e.g. Enterprise Data Model – simplified ER Diagram) Processes – data flow diagrams, process decomposition, etc. Data Network – topology diagram (like fig 1.9) 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)

Information Engineering A data-oriented methodology to create and maintain information systems Top-down planning: a generic IS planning methodology for obtaining a broad understanding of the IS needed by the entire organization Four steps to Top-Down planning: Planning Analysis Design Implementation

Information Systems Planning (Table 2-1) Purpose: align information technology with organization’s business strategies Three steps: Identify strategic planning factors Identify corporate planning objects Develop enterprise model

Identify Strategic Planning Factors (Table 2-2) Organization goals – what we hope to accomplish Critical success factors – what MUST work in order for us to survive Problem areas – weaknesses we now have

Identify Corporate Planning Objects (Table 2-3) Organizational units – departments Organizational locations Business functions – groups of business processes Entity types – the things we are trying to model for the database Information systems – application programs

Develop Enterprise Model Functional decomposition See Figure 2-2 Enterprise data model See Figure 2-1 Planning matrixes See Figure 2-3

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

Planning Matrixes Describe relationships between planning objects in the organization Types of matrixes: Function-to-data entity Location-to-function Unit-to-function IS-to-data entity Supporting function-to-data entity IS-to-business objective

Example business function-to-data entity matrix (Fig. 2-3) Business Planning X X X X Product Development X X X X Materials Management X X X X X X Order Fulfillment X X X X X X X X X Order Shipment X X X X X X Sales Summarization X X X X X Production Operations X X X X X X X Finance and Accounting X X X X X X X X Customer Product Raw Material Order Work Center Work Order Invoice Equipment Employee Business Function (users) Data Entity Types

Two Approaches to Database and IS Development SDLC System Development Life Cycle Detailed, well-planned development process Time-consuming, but comprehensive Long development cycle Prototyping Rapid application development (RAD) Cursory attempt at conceptual data modeling. Define database during development of initial prototype Repeat implementation and maintenance activities with new prototype versions

Systems Development Life Cycle (Figures 2-4, 2-5) Project Identification and Selection Project Initiation and Planning Analysis Physical Design Implementation Maintenance Logical Design

Systems Development Life Cycle (cont.) (Figures 2-4, 2-5) Maintenance Purpose --preliminary understanding Deliverable –request for project Database activity – enterprise modeling Project Identification and Selection Project Identification and Selection Project Initiation and Planning Analysis Physical Design Implementation Maintenance Logical Design

Systems Development Life Cycle (cont.) (figures 2-4, 2-5) Purpose – state business situation and solution Deliverable – request for analysis Database activity – conceptual data modeling Project Initiation and Planning Project Identification and Selection Project Initiation and Planning Analysis Physical Design Implementation Maintenance Logical Design

Systems Development Life Cycle (cont.) (figures 2-4, 2-5) Purpose – thorough analysis Deliverable – functional system specifications Database activity – conceptual data modeling Analysis Project Identification and Selection Project Initiation and Planning Analysis Physical Design Implementation Maintenance Logical Design

Systems Development Life Cycle (cont.) (figures 2-4, 2-5) Maintenance Purpose – information requirements structure Deliverable – detailed design specifications Database activity – logical database design Logical Design Project Identification and Selection Project Initiation and Planning Analysis Physical Design Implementation Maintenance Logical Design

Systems Development Life Cycle (cont.) (figures 2-4, 2-5) Purpose – develop technology specs Deliverable – program/data structures, technology purchases, organization redesigns Database activity – physical database design Physical Design Project Identification and Selection Project Initiation and Planning Analysis Physical Design Implementation Maintenance Logical Design

Systems Development Life Cycle (cont.) (figures 2-4, 2-5) Purpose – programming, testing, training, installation, documenting Deliverable – operational programs, documentation, training materials Database activity – database implementation Implementation Project Identification and Selection Project Initiation and Planning Analysis Physical Design Implementation Maintenance Logical Design

Systems Development Life Cycle (cont.) (figures 2-4, 2-5) Purpose – monitor, repair, enhance Deliverable – periodic audits Database activity – database maintenance Maintenance Project Identification and Selection Project Initiation and Planning Analysis Physical Design Implementation Maintenance Logical Design

Packaged Data Models Model components that can be purchased, customized, and assembled into full-scale data models Advantages Reduced development time Higher model quality and reliability Two types: Universal data models Industry-specific data models

CASE Computer-Aided Software Engineering (CASE) – software tools providing automated support for systems development Three database features: Data modeling – entity-relationship diagrams Code generation – SQL code for table creation Repositories – knowledge base of enterprise information

Managing Projects Project – a planned undertaking of related activities to reach an objective that has a beginning and an end Involves use of review points for: Validation of satisfactory progress Step back from detail to overall view Renew commitment of stakeholders Incremental commitment – review of systems development project after each development phase with rejustification after each phase

Managing Projects: People Involved Systems analysts Database analysts Users Programmers Database/data administrators Systems programmers, network administrators, testers, technical writers

Figure 2-8a Gantt Chart Shows time estimates of tasks

Figure 2-8b PERT chart Shows dependencies between tasks

Database Schema Physical Schema Physical structures – covered in chapters 5 and 6 Conceptual Schema E-R models – covered in chapters 3 and 4 External Schema User Views Subsets of Conceptual Schema Can be determined from business-function/data entity matrices DBA determines schema for different users

Different people have different views of the database…these are the external schema The internal schema is the underlying design and implementation

Figure 2-11 Three-tiered client/server database architecture

Pine Valley Furniture Preliminary data model (Figure 2-12)

964 database development process intro1

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