Phases in Database Development Life Cycle. - Softkhazana

The database development process comprises a series of phases. The major phases in information engineering are:

• Planning
• Analysis
• Design
• DBMS Selection
• Implementation
• Maintenance

Database planning

The database-planning phase begins when a customer requests to develop a database project. It is set of tasks or activities, which decide the resources required in the database development and time limits of different activities. During planning phase, four major activities are performed.

• Review and approve the database project request.
• Prioritize the database project request.
• Allocate resources such as money, people and tools.
• Arrange a development team to develop the database project.

Database planning should also include the development of standards that govern how data will be collected, how the format should be specified, what necessary documentation will be needed.

Requirements Analysis

Requirements analysis is done in order to understand the problem, which is to be solved. It is very important activity for the development of database system. The person responsible for the requirements analysis is often called "Analyst".

In requirements analysis phase, the requirements and expectations of the users are collected and analyzed. The collected requirements help to understand the system that does not yet exist. There are two major activities in requirements analysis.        

• Problem understanding or analysis
• Requirement specifications.

Design

The database design is the major phase of information engineering. In this phase, the information models that were developed during analysis are used to design a conceptual schema for the database and to design transaction and application.

• In conceptual schema design, the data requirements collected in Requirement Analysis phase are examined and a conceptual database schema is produced.
• In transaction and application design, the database applications analyzed in Requirement Analysis phase are examined and specifications of these applications are produced. There are two major steps in design phase:

• Database Design
• Process Design

DBMS

In this phase an appropriate DBMS is selected to support the information system. A number of factors are involved in DBMS selection. They may be technical and economical factors. The technical factors are concerned with the suitability of the DBMS for information system. The following technical factors are considered.

• Type of DBMS such as relational, object-oriented etc
• Storage structure and access methods that the DBMS supports.
• User and programmer interfaces available.
• Type of query languages.
• Development tools etc. 

Implementation

After the design phase and selecting a suitable DBMS, the database system is implemented. The purpose of this phase is to construct and install the information system according to the plan and design as described in previous phases. Implementation involves a series of steps leading to operational information system that includes creating database definitions (such as tables, indexes etc), developing applications, testing the system, developing operational procedures and documentation, training the users and populating the database. In the context of information engineering, it involves two steps.

•  Database definitions.
• Creating applications.

Operational Maintenance 

Once the database system is implemented, the operational maintenance phase of the database system begins. The operational maintenance is the process of monitoring and maintaining the database system. Maintenance includes activities such as adding new fields, changing the size of existing field, adding new tables, and so on. As the database system requirement change, it becomes necessary to add new tables or remove existing tables and to reorganize some files by changing primary access methods or by dropping old indexes and constructing new ones. Some queries or transactions may be rewritten for better performance. Database tuning or reorganization continues throughout the life of database and while the requirements keep changing.