The Database Development Process 1 Objectives n n

The Database Development Process 1

Objectives n n n n 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 2

Enterprise Data Model n n n n 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 3

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 4

Information Systems Architecture (ISA) n n Conceptual blueprint for organization’s desired information systems structure Consists of: n n n 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) 5

Information Engineering n n n 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: n n Planning Analysis Design Implementation 6

Information Systems Planning (Table 2 -1) n n Purpose: align information technology with organization’s business strategies Three steps: 1. 2. 3. Identify strategic planning factors Identify corporate planning objects Develop enterprise model 7

Identify Strategic Planning Factors (Table 2 -2) n n n 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 8

Identify Corporate Planning Objects (Table 2 -3) n n n 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 9

Develop Enterprise Model n Functional decomposition n See n Enterprise data model n See n Figure 2 -2 Figure 2 -1 Planning matrixes n See Figure 2 -3 10

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 11

Planning Matrixes n n Describe relationships between planning objects in the organization Types of matrixes: Function-to-data entity n Location-to-function n Unit-to-function n IS-to-data entity n Supporting function-to-data entity n IS-to-business objective n 12

Data Entity Types Business Function (users) Business Planning Product Development Materials Management Order Fulfillment Order Shipment Sales Summarization Production Operations Finance and Accounting Customer Product Raw Material Order Work Center Work Order Invoice Equipment Employee Example business function-todata entity matrix (Fig. 2 -3) X X X X X X X X X X X X X 13

Two Approaches to Database and IS Development n SDLC n n n System Development Life Cycle Detailed, well-planned development process Time-consuming, but comprehensive Long development cycle Prototyping n n 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 14

Systems Development Life Cycle (Figures 2 -4, 2 -5) Project Identification and Selection Project Initiation and Planning Analysis Logical Design Physical Design Implementation Maintenance 15

Systems Development Life Cycle (cont. ) (Figures 2 -4, 2 -5) Project Identification and Selection Purpose --preliminary understanding Deliverable –request for project Project Initiation and Planning Analysis Logical Design Physical Design Database activity – enterprise modeling Implementation Maintenance 16

Systems Development Life Cycle (cont. ) (figures 2 -4, 2 -5) Project Identification and Selection Purpose – state business situation and solution Deliverable – request for analysis Project Initiation and Planning Analysis Logical Design Physical Design Database activity – conceptual data modeling Implementation Maintenance 17

Systems Development Life Cycle (cont. ) (figures 2 -4, 2 -5) Project Identification and Selection Purpose – thorough analysis Deliverable – functional system specifications Project Initiation and Planning Analysis Logical Design Physical Design Database activity – conceptual data modeling Implementation Maintenance 18

Systems Development Life Cycle (cont. ) (figures 2 -4, 2 -5) Project Identification and Selection Purpose – information requirements structure Deliverable – detailed design specifications Project Initiation and Planning Analysis Logical Design Physical Design Database activity – logical database design Implementation Maintenance 19

Systems Development Life Cycle (cont. ) (figures 2 -4, 2 -5) Purpose – develop technology specs Deliverable – program/data structures, technology purchases, organization redesigns Project Identification and Selection Project Initiation and Planning Analysis Logical Design Physical Design Database activity – physical database design Implementation Maintenance 20

Systems Development Life Cycle (cont. ) (figures 2 -4, 2 -5) Purpose – programming, testing, training, installation, documenting Deliverable – operational programs, documentation, training materials Project Identification and Selection Project Initiation and Planning Analysis Logical Design Physical Design Database activity – database implementation Implementation Maintenance 21

Systems Development Life Cycle (cont. ) (figures 2 -4, 2 -5) Project Identification and Selection Purpose – monitor, repair, enhance Deliverable – periodic audits Project Initiation and Planning Analysis Logical Design Physical Design Database activity – database maintenance Implementation Maintenance 22

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Packaged Data Models n n Model components that can be purchased, customized, and assembled into full-scale data models Advantages n n n Reduced development time Higher model quality and reliability Two types: n n Universal data models Industry-specific data models 29

CASE n n Computer-Aided Software Engineering (CASE) – software tools providing automated support for systems development Three database features: Data modeling – entity-relationship diagrams n Code generation – SQL code for table creation n Repositories – knowledge base of enterprise information n 30

Managing Projects n n 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 n Step back from detail to overall view n Renew commitment of stakeholders n n Incremental commitment – review of systems development project after each development phase with rejustification after each phase 31

Managing Projects: People Involved n n n Systems analysts Database analysts Users Programmers Database/data administrators Systems programmers, network administrators, testers, technical writers 32

Figure 2 -8 a Gantt Chart Shows time estimates of tasks 33

Figure 2 -8 b PERT chart Shows dependencies between tasks 34

Database Schema n Physical Schema n n Conceptual Schema n n Physical structures – covered in chapters 5 and 6 E-R models – covered in chapters 3 and 4 External Schema n n User Views Subsets of Conceptual Schema Can be determined from business-function/data entity matrices DBA determines schema for different users 35

Different people have different views of the database…these are the external schema The internal schema is the underlying design and implementation 36

Figure 2 -11 Three-tiered client/server database architecture 37

Pine Valley Furniture Preliminary data model (Figure 2 -12) 38

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