3.0 DATA BASE SYSTEM DEVELOPMENT LIFE CYCLE
A database
is usually a fundamental component of the information system, especially in
business oriented systems. Thus database design is part of system development.
The following picture shows how database design is involved in the system
development life cycle.
There are various methods of how the different phases of information system design, analysis and implementation can be done. Here the main tasks or goals are described but no method is introduced.
Database Planning
The
database planning includes the activities that allow the stages of the database
system development lifecycle to be realized as efficiently and effectively as
possible. This phase must be integrated with the overall Information System
strategy of the organization.
The very first step in database planning is to define the mission statement and objectives for the database system. That is the definition of:
- the major aims of the database system
- the purpose of the database system
- the supported tasks of the database system
- the resources of the database system
The very first step in database planning is to define the mission statement and objectives for the database system. That is the definition of:
- the major aims of the database system
- the purpose of the database system
- the supported tasks of the database system
- the resources of the database system
Systems Definition
In
the systems definition phase, the scope and boundaries of the database
application are described. This description includes:
- links with the other information systems of the organization
- what the planned system is going to do now and in the future
- who the users are now and in the future.
The major user views are also described. what is required of a database system from the perspectives of particular job roles or enterprise application areas.
- links with the other information systems of the organization
- what the planned system is going to do now and in the future
- who the users are now and in the future.
The major user views are also described. what is required of a database system from the perspectives of particular job roles or enterprise application areas.
Requirements Collection and Analysis
During
the requirements collection and analysis phase, the collection and analysis of
the information about the part of the enterprise to be served by the database
are completed. The results may include:
- the description of the data used or generated
- the details how the data is to be used or generated
- any additional requirements for the new database system
- the description of the data used or generated
- the details how the data is to be used or generated
- any additional requirements for the new database system
Database Design
The
database design phase is divided into three steps:
- conceptual database design
- logical database design
- physical database design
- conceptual database design
- logical database design
- physical database design
Database Management System Selection
This
in an optional phase. When there is a need for a new database management system
(DBMS), this phase is done. DBMS means a database system like Access, SQL
Server, MySQL,
Oracle.
In this phase the criteria for the new DBMS are defined. Then several products are evaluated according to the criteria. Finally the recommendation for the selection is decided.
In this phase the criteria for the new DBMS are defined. Then several products are evaluated according to the criteria. Finally the recommendation for the selection is decided.
Application Design
In
the application design phase, the design of the user interface and the
application programs that use and process the database are defined and designed.
Prototyping
The
purpose of a prototype is to allow the users to use the prototype to identify
the features of the system using the computer.
There are horizontal and vertical prototypes. A horizontal prototype has many features (e.g. user interfaces) but they are not working. A vertical prototype has very few features but they are working.
There are horizontal and vertical prototypes. A horizontal prototype has many features (e.g. user interfaces) but they are not working. A vertical prototype has very few features but they are working.
Implementation
During
the implementation phase, the physical realization of the database and
application designs are to be done. This is the programming phase of the
systems development.
Data Conversion and Loading
This
phase is needed when a new database is replacing an old system. During this
phase the existing data will be transferred into the new database.
Testing
Before
the new system is going to live, it should be thoroughly tested. The goal of
testing is to find errors! The goal is not to prove the software is working
well.
Operational Maintenance
The
operational maintenance is the process of monitoring and maintaining the
database system.
Monitoring means that the performance of the system is observed. If the performance of the system falls below an acceptable level, tuning or reorganization of the database may be required.
Maintaining and upgrading the database system means that, when new requirements arise, the new development life cycle will be done.
Monitoring means that the performance of the system is observed. If the performance of the system falls below an acceptable level, tuning or reorganization of the database may be required.
Maintaining and upgrading the database system means that, when new requirements arise, the new development life cycle will be done.
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