Database System Development
Lifecycle
Chapter 4
Learning Objectives
By the end of this chapter, you should be able to:
1.List the three designs involved in the database design
phase;
2.State three important sections in the conceptual
design phase; and
3.Explain the purpose of the six phases involved in the
database development life cycle.
Introduction
• Involves the following process:
– designing
– implementing
– organising
• A component of information system and is
governed by one life cycle called Database
Development Life Cycle (DDLC).
DDLC
• Based on data orientation approach.
• The characteristics of data become the basis for
designing the database scheme.
• All system functions are developed based on the
scheme or database structure.
• Functions of a system changes according to the
requirements of users but the database scheme usually
remains stable without major changes.
• Life cycle consists of 6 phases.
• These phases are iterative processes where each phase
may be repeated a number of times in order to obtain
a comprehensive feedback, especially from users.
6 phases of DDLC
•
•
•
•
•
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Database Planning
Database Design
Implementation and Downloading
Testing and Evaluation
Operation
Maintenance and Evolution
Database Planning
• 3 basic factors that influence activity flow of database
planning:
– Tasks that need to be carried out.
– Existing resources to implement it; and
– Finance or allocation provided.
• Purpose of planning phase:
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–
–
–
–
To Analyse the Current Situation of an Organisation
Defining Problems and Constraints
Defining Objective
Defining Scope and Boundary
Feasibility Research
Database Design
• Most important stage in DDLC.
• Influences the whole performance of the
database being developed.
• Purpose of database design:
– Represent data and the relationship between data.
– Provide a data model to support all required
transactions.
– To determine that the system design has fulfilled the
requirements of users and the system.
Activities conducted during DB design
• Conceptual Design
– Data Modelling
– Normalisation
– Data Model Validation
• Logical Design
– Translating each entity, attribute and relationship into a
data representation form compatible with a DBMS model.
• Physical Design
– Involves physical aspects of data saved in storage and the
performance of the system.
Implementation & Downloading
• Developers can choose whether to develop a prototype or the
whole actual system.
• A prototype is a model that functions like an end system but is
not equipped with full features. However, it can be used to
test whether the basic functions of the system can be
operated as planned
• Activities of the implementation phase:
– Setting Up a DBMS
– Creating a Database
– Data Downloading/Changing
Testing & Evaluation
• Database Testing and Application Procedures
– The process of database testing is composed of
integration test, unit test and system test.
• Database Evaluation
– The evaluation to be conducted will be on
performance and system security.
Operation
• Operation phase and support system begins when the system
has operated in an actual environment and ends when it is
replaced by a new system.
• A new system can operate by using several approaches as
follows:
–
–
–
–
Direct Transition Plan
Parallel Transition Plan
Pioneer Transition Plan
Staggered Transition Plan
Maintenance & Evolution
• Process of monitoring and maintaining the performance of
the system and database.
• If the system is at an unsatisfactory level, reorganisation and
readjustment of the database need to be carried out.
• Maintenance must be conducted from time to time for the
purposes of:
– Correcting errors in the system, system competency and other factors
– Changes to the rules and organisational policy.
– System needs to be changed or upgraded to the latest version to
support the needs and requirements of users as well as the
organisation.
Activity 1
• Discuss the major reasons for project failures
• In your words, explain what is a feasibility
study?
• Explain the various data gathering methods
you are aware of.
• Distinguish between a top down and bottom
up database design approaches.