1 IS 4420 Database Fundamentals Chapter 2: Database Development Process Leon Chen

2 Overview Definition of terms Definition of terms System development life cycle System development life cycle Prototyping approach Prototyping approach Three-schema approach Three-schema approach Packaged data models Packaged data models Project management Project management

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

4 Figure 2-1 Segment from enterprise data model (Pine Valley Furniture Company) Enterprise data model describes the high-level entities in an organization and the relationship between these entities

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

6 Information Engineering A data-oriented methodology to create and maintain information systems 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 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: Four steps to Top-Down planning:  Planning  Analysis  Design  Implementation

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

8 Systems Development Life Cycle Project Identification and Selection Project Initiation and Planning Analysis Physical Design Implementation Maintenance Logical Design Waterfall

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

10 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 Identification and Selection Project Initiation and Planning Analysis Physical Design Implementation Maintenance Logical Design

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

12 Entity Relationship Diagram (ERD)

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

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15 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 Project Identification and Selection Project Initiation and Planning Analysis Physical Design Implementation Maintenance Logical Design

16 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 Project Identification and Selection Project Initiation and Planning Analysis Physical Design Implementation Maintenance Logical Design

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

18 Systems Development Life Cycle Project Identification and Selection Project Initiation and Planning Analysis Physical Design Implementation Maintenance Logical Design Enterprise modeling Conceptual data modeling Logical database design Physical database design and definition Database implementation Database maintenance Database Development Process

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

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

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

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

24 Managing Projects Project – a planned undertaking of related activities to reach an objective that has a beginning and an end Project – a planned undertaking of related activities to reach an objective that has a beginning and an end Project management is a balance of: Project management is a balance of:  Scope  Schedule  Cost  Quality Project management life cycle Project management life cycle 1. Initiation 2. Planning and scheduling 3. Control 4. Closing Project management tool: Microsoft Project Project management tool: Microsoft Project Incremental (creeping) commitment – review of systems development project after each development phase with rejustification after each phase Incremental (creeping) commitment – review of systems development project after each development phase with rejustification after each phase

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

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

27 Figure 2-8b PERT chart (Program Evaluation and Review Technique) Shows dependencies between tasks

28 Systems Development Life Cycle Project Identification and Selection Project Initiation and Planning Analysis Physical Design Implementation Maintenance Logical Design Enterprise modeling Conceptual data modeling Logical database design Physical database design and definition Database implementation Database maintenance Database Development Process