DATABASE SYSTEM DEVELOPMENT LIFECYLE Summary
DATABASE SYSTEM DEVELOPMENT LIFECYLE Summary
DATABASE SYSTEM DEVELOPMENT LIFECYLE Summary
Database is a shared collection of logically related data that designed to meet the requirement
needed for a certain organization.
Database system development lifecycle is the process of designing, implementing and
maintaining a database system to meet an information needs of an organization. Database
system development lifecycle it is designed so as to reduce the risks of failure of some projects,
because some software projects fails due to the following reasons:
i. Lack of complete requirement specification of a project.
ii. Lack of an appropriate development methodology.
iii. Poor decomposition of designs into manageable components.
Database planning should also include the development standard that govern how data will be
collected, how the format should be specified, what documentation will be needed as well as
how design and implementation should be proceed .
Database planning
System definition
Database design
Conceptual database
Implementation
Prototyping
Testing
User view 6
User view1
User view5
User view5
User view 3
data
User view 2
User view 3
User view 4
In managing requirement of database system in multiple users view it includes three approaches
Centralized approach
View integration approach
Combination of both approaches
CENTRALIZED APPROACH
In this approach the requirement for each user view are merged into a single set of requirements
for the new database system and data model which are used to represent all user view are created
during database design
4.DATABASE DESIGN
It involves the process of creating a design that will support the organization’s requirement,
mission statement and objectives for the required database system
There are two main approach to design a database system which are Bottom-up and top-down
approach.
Bottom-up approach. begin at the fundamental level of attributes properties of entities
and relationships which through analysis of the associations between attributes are grouped into
relations that represent types of entities and relationships between entities. The bottom-up
approach is appropriate for the design of simple databases with a small number of attribute.
Bottom-up approach is not good when dealing with design of complex databases with very large
number of attributes.
Top-down approach is good strategy for the design of complex databases with very larger
number of attributes. This approach starts with the development of data models that contain a
few high-level entities and relationships and then applies successive top-down to identify lower-
level entities, relationships, and the associated attributes. The top-down approach is illustrated
using the concepts of the Entity-Relationship (ER) model.
There are other two approaches to database design which are inside-out approach and the mixed
strategy approach.
The inside-out approach is likely related to the bottom-up approach, but it differs by first
identifying a set of major entities and then spreading out to consider other entities, relationships,
and attributes associated with those first identified.
The mixed strategy approach uses both the bottom-up and top-down approach for various parts
of the model before finally combining all parts together.
Data modeling
Data modeling has two purpose which are as follow:-
To facilitate communication about the information requirement.
To assist the understanding of meaning of the data
So in creating a data model requires someone to ask questions and getting answers about entities,
attributes and relationships.
However data model can be used to show the designer’s understanding of the information
requirement of an organization.
Criteria for data model
Simplicity means that easy of understanding by both technical information
system professional’s and non technical users.
No redundancy means that data are not duplicates so it ensures high
performance
Diagrammatic representation means that the ability of representing a model
using a easily understanding diagrammatic notation
Share ability means that the ability to be shared by many, not specific for a
certain user or technology
Integrity it involves the consistency with the way enterprise uses and manages
information
Extensibility means that ability to evolve to support new requirement with the
minimum effect on the existing users
Expressibility means that the ability to distinguish between different data,
relational data and constraints
EXTERNAL SCHEMA
CONCEPTUAL SCHEMA
INTERNAL SCHEMA
PHYSICAL SCHEMA
6.APPLICATION DESIGN
It involves design of user interface and design of transaction .
Database transaction is a series of action carried out by a single user or application program
7.PROTOTYPING
It involves building a working model of the database system which allows the designer or users to
visualize and evaluates the system.
8. IMPLEMENTATION
Is the physical realization of the database and application designs
9.DATA CONVERSION AND LOADING
It involves transferring any existing data into new database and converting any existing application to
run on the new database.
10.TESTING
I the process of running the database system with the intent of finding errors
11.OPERATIONAL MAINTENANCE
Is the process of monitoring and maintaining the system installation.
References :
Database Systems A Practical Approach to Design, Implementation, and Management, Thomas Connolly,
Carolyn Begg Six Edition.