Database Design Process
After
studying this chapter, you should be
able to:
- Major Topic From Module
– Database Design process
- Lesson title: Database System Development Life cycle.
- After studying this chapter, you should be able to(Learning Outcomes):
– Explain Database system Development
Lifecycle(DSDLC).
– State the stages/Phases of DSDLC.
– Explain each main stages of the DSDLC.
– Explain Database Design process.
Introduction
What are main phases in System Development Life
Cycle (SDLC)?
Database System Development Life Cycle
- Database system is a fundamental component of the larger organization.
- It is also a fundamental and important component of information system.
- Database system development life cycle is inherently associated with the life cycle of the information system.
- With a small number of users, the life cycle need not be very complex.
- Designing a medium to large database systems with tens to thousands of users, using hundreds of queries and application programs, the life cycle can become extremely complex.
Stages of DSDLC
- Database planning
- System definition
- Requirements collection and analysis
- Database design
- DBMS selection (optional)
- Application design
- Prototyping (optional)
- Data conversion and loading
- Implementation
- Testing
- Operational maintenance
Stages of DSDLC
üDatabase Planning
• Planning how the stages of
the life cycle can be realized
most efficiently and
effectively.
Stages of DSDLC
üDatabase Planning
üSystem definition
• Specifying the scope and
boundaries of the database
system, including the major
user views, its users, and
application areas.
Stages of DSDLC
üDatabase Planning
üSystem definition
üRequirements collection and analysis
• Collection and analysis of
the requirements for the
new database system.
Stages of DSDLC
üDatabase Planning
üSystem definition
üRequirements collection and analysis
üDatabase design
• Conceptual, logical, and physical design of the database.
Stages of DSDLC
üDatabase Planning
üSystem definition
üRequirements collection and analysis
üDatabase design
üDBMS selection (optional)
• Selecting a suitable DBMS
for the database system.
Stages of DSDLC
üDatabase Planning
üSystem definition
üRequirements collection and analysis
üDatabase design
üDBMS selection (optional)
üApplication design
• Designing the user interface and the application programs that use and process the database.
Stages of DSDLC
üDatabase Planning
üSystem definition
üRequirements collection and analysis
üDatabase design
üDBMS selection (optional)
üApplication design
üPrototyping (optional)
• Building a working model of the database system, which allows the designers or users to visualize and evaluate how the final system will look and function.
Stages of DSDLC
üDatabase Planning
üSystem definition
üRequirements collection and analysis
üDatabase design
üDBMS selection (optional)
üApplication design
üPrototyping (optional)
üImplementation
• Creating the physical database definitions and the application programs
Stages of DSDLC
üDatabase Planning
üSystem definition
üRequirements collection and analysis
üDatabase design
üDBMS selection (optional)
üApplication design
üPrototyping (optional)
üImplementation
üData conversion and loading
• Loading data from the old system to the new system and, where possible, converting any existing applications to run on the new database.
Stages of DSDLC
üDatabase Planning
üSystem definition
üRequirements collection and analysis
üDatabase design
üDBMS selection (optional)
üApplication design
üPrototyping (optional)
üImplementation
üData conversion and loading
üTesting
• Database system is tested for errors and validated against the requirements specified by the users.
Stages of DSDLC
üDatabase Planning
üSystem definition
üRequirements collection and analysis
üDatabase design
üDBMS selection (optional)
üApplication design
üPrototyping (optional)
üImplementation
üData conversion and loading
üTesting
üOperational maintenance
• Database system is fully implemented.
• The system is continuously monitored and maintained.
• When necessary, new requirements are incorporated into the database system through the preceding stages of the life cycle.
Stages of DSDLC
üDatabase Planning
üSystem definition
üRequirements collection and analysis
üDatabase design
üDBMS selection (optional)
üApplication design
üPrototyping (optional)
üImplementation
üData conversion and loading
üTesting
üOperational maintenance
• Stages of the database system development life cycle are not strictly sequential, Some of them working as feedback loops.
Database system Development Life cycle
Stages of DSDLC
Database Planning
• Database planning must be integrated with the overall Information System strategy of the organization.
• Define the mission statement
– An important first step in database planning..
– The mission statement defines the major aims of the database system.
Ex of Care:- To serve individuals and families in the poorest communities in the world.
– This statement define by Director/owner of the company.
• Identifying the mission objectives
– Next activity involves identifying the mission objectives.
– Define Objective:- A specific result that a person or system aims to achieve within a time frame and with available resources.
– Each objective identify each tasks.
– The assumption is that if the database system supports the mission objectives then the mission statement should be met.
• Database planning also include following
Questions.
– how data will be collected?
– what necessary documentation will be needed?
– how design and implementation should proceed?
System Definition
• Describes the scope and boundaries of the database application and definition the major user views.
• A database have more than one users.
• Identifying user view is an important aspect.
• User view Defines what is required of a database system from the position of a particular job role.
Requirements Collection and Analysis
• The process of collecting and analyzing information(Same as SAD).
• Identify the requirements for the new system.
• Collection methods are
1. Interview
2. Questionnaires
3. Onsite observations
Database Design
• The process of creating a design that will support the enterprise’s mission statement and mission objectives for the required database system.
• There are three phases of database design
– Conceptual
– Logical,
– Physical Design
Conceptual database design
• Conceptual database design, and involves the creation of a conceptual data model of the part of the large project.
• Data model build according to user’s requirement.
• Conceptual database design independent from
– DBMS Software
– Application program
– Programming language
– Hardware
Conceptual database design
• Identify Entities and attributes.
• Draw the E-R diagram.
• The conceptual data model is a source of information for logical database design.
Logical database design
• The process of constructing a model of the data based on a specific data model
• Independent of a particular DBMS and other physical considerations.
• The logical data model is based on the target data model for the database
• The model is tested and validated against the users’
requirements
• Normalization technique used for test the correctness of the data model.
Logical database design
• The logical data model is a source of information for the physical database design.
• The logical model also serves an important role during the operational maintenance stage.
• Logical structure for the database, which describes relations and constraints.
Physical database design
• It is the third and final phase of the database design process,
• Here designer decides how the database is to be implemented.
• Developing the physical database design, we must first identify the target DBMS.
• Therefore, physical design is adjust to a specific
DBMS system.
Physical database design
• physically implement the logical database design.
– creating a set of relational tables
– identifying the specific storage structures and access methods for the data.
– designing security protection for the system
DBMS Selection
• If no DBMS exists, you should select a appropriate
DBMS.
• If you are going to select a DBMS first you cans check the feature against requirements.
Application Design
• The design of the user interface and the application programs that use and process the database.
• Database and application design are parallel activities.
• Designing the application programs that access the database and designing the transactions(Database Access methods).
• These interface present the required information in a
‘user-friendly’ way.
Prototyping
• A prototype is a working model that does not normally have all the required features or provide all the functionality of the final system.
• The main purpose of developing a prototype database system
– allow users to use the prototype
– Features of the system that work well,
– Check inadequate or not.
– Suggest improvements.
– New features to the database system.
Implementation
• On completion of the design stages
• Implement the database and the application programs.
• The database implementation is achieved using the
Data Definition Language (DDL) .
• Any specified user views are also implemented at this stage.
Data Conversion and Loading
• Transferring any existing data into the new database and converting any existing applications to run on the new database.
• This stage is required only when a new database system is replacing an old system.
Testing
• The process of running the database system with the intent of finding errors.
• Testing cannot show the absence of faults; it can show only that software faults are present.
Operational Maintenance
• The process of monitoring and maintaining the database system following installation.
• involves the following activities
– Monitoring the performance of the system. If the performance falls below an acceptable level, tuning or reorganization of the database may be required.
– Maintaining and upgrading the database system (when required). New requirements are incorporated into the database system through the preceding stages of the lifecycle.
Summary
• Database Planning
• System definition
• Requirements collection
• and analysis
• Database design
– Conceptual
– Logical,
– Physical Design
• DBMS selection (optional)
• Application design
• Prototyping (optional)
• Implementation
• Data conversion and loading
• Testing
• Operational maintenance
BY: C.SIVAKARAN
JAFFNA COLLEGE OF T0ECHNOLOGY
SRI LANKA
SRI LANKA
