Database Development Chapter 2

• Database development is covered in chapter 2.

The Enterprise Data Model

• The first step in database development is establishing the Enterprise Data Model.
• The Enterprise Data Model specifies the scope and general content of the database.
• It provides an overall picture of organizational data at a high level of abstraction.
• The Enterprise Data Model includes entity-relationship diagrams.
• The Enterprise Data Model has descriptions of entity types.
• The Enterprise Data Model defines relationships between entities.
• Business rules are part of the Enterprise Data Model.
• High-level entities and their relationships are described by the Enterprise Data Model.

Database and IS Development

• There are two approaches to database and Information Systems development: SDLC and Prototyping.

System Development Life Cycle (SDLC)

• SDLC stands for System Development Life Cycle.
• The SDLC is a detailed and well-planned development process.
• The SDLC is time-consuming and comprehensive.
• The SDLC has a long development cycle.

Prototyping

• RAD is rapid application development.
• Database definition occurs during the initial prototype development in prototyping.
• Implementation and maintenance activities are repeated with new prototype versions in prototyping.
• There is a cursory attempt at conceptual data modeling in prototyping.

SDLC Phases

• Planning is the first phase, with the purpose of preliminary understanding and the deliverable being a request for study.
• Thorough requirements analysis and structuring are done in the Analysis phase, with functional system specifications as the deliverable.
• Information requirements elicitation and structure are the purpose of the Logical Design phase, and detailed design specifications are the deliverable.
• Developing technology and organizational specifications is the purpose of the Physical Design phase; program/data structures, technology purchases, and organization redesigns are the deliverable.
• The purpose of the Implementation phase is programming, testing, training, installation and documentation.
• Operational programs, documentation, and training materials are the deliverable of the Implementation phase.
• Monitoring, repair, and enhancement are the purpose of the Maintenance phase, with periodic audits being the deliverable.
• Enterprise and early conceptual data modeling is a database activity during the planning phase.
• Thorough and integrated conceptual data modeling is a database activity during the analysis phase.
• Logical database design (transactions, forms, displays, views, data integrity and security) is a database activity during the logical design phase.
• Physical database design (define database to DBMS, physical data organization, database processing programs) is a database activity during the physical design phase.
• Database implementation, including coded programs, documentation, installation and conversion is a database activity during the Implementation phase.
• Database maintenance, performance analysis and tuning, and error corrections are database activities during the Maintenance phase.

Prototyping Methodology

• Inefficient prototypes result in system revisions.
• Conceptual data modeling involves analyzing requirements and developing a preliminary data model.
• The logical database design phase involves analyzing requirements in detail and integrating database views into a conceptual data model.
• A physical database design and definition phase defines new database content to DBMS, determines physical data organization, and develops database processing programs.
• Database implementation includes coding database processing and installing new database contents from existing data sources.
• Database maintenance entails analyzing the database to ensure it meets application needs and fix errors.
• Database maintenance includes improved performance tuning.

Packaged Data Models

• Model components are purchased to be customized and be assembled into full-scale data models.
• Advantages of packaged data models include reduced development time.
• Higher model quality and reliability are advantages of packaged data models.
• Universal and industry-specific data models are available.

Managing Projects

• A project is a planned undertaking of related activities with a beginning and an end to reach an objective.
• Projects involve review points for validation of satisfactory progress to step back from detail to overall view.
• Review points help renew commitment of stakeholders.
• Review of systems development project after each development phase with re-justification after each phase is incremental commitment.
• Project roles include business analysts, systems analysts, database analysts and data modelers.
• Users, programmers, database architects, data administrators, project managers, and other technical experts also involved in projects.

Database Schema

• Internal level describes how data is stored and the way perceived by the DBMS/OS.
• Conceptual level describes what data is stored in the DB, its relationships, and the way perceived by the DBA/programmers.
• External level describes parts of the DB a user is interested in and how it is perceived by the end user.
• Database external schema reflects the different views people have of the database, while internal schema is the underlying design and implementation.