Description of the Stages in the DBLC
The five stages of the Database Life Cycle associated with each task:
The stages and the principal task associated with each are listed below.
- Requirements analysis: identify business objects
- Logical design: create a conceptual model
- Physical design: tweak database for performance
- Implementation: create SQL tables
- Monitoring, modification, maintenance: update records
Modern Database Life Cycle (DBLC) contains six phases:
- database initial study,
- database design,
- implementation and loading,
- testing and evaluation,
- operation, and
- maintenance and evolution.
Database Design and Theory
Database Initial Study:
In the Database initial study, the designer must examine the current system's operation within the company and determine how and why the current system fails.
The overall purpose of the database initial study is to:
- Analyze the company situation.
- Define problems and constraints.
- Define objectives.
- Define scope and boundaries.
a. Analyze the Company Situation:
The company situation describes the general conditions in which a company operates, its organizational structure, and its mission.
To analyze the company situation, the database designer must discover what the company's operational components are, how they function, and how they interact.
b. Define Problems and Constraints:
The designer has both formal and informal sources of information. The process of defining problems might initially appear to be unstructured. Company end users are often unable to describe precisely the larger scope of company operations or to identify the real problems encountered during company operations.
c. Define Objectives:
A proposed database system must be designed to help solve at least the major problems identified during the problem discovery process. In any case, the database designer must begin to address the following questions:
- What is the proposed system's initial objective?
- Will the system interface with other existing or future systems in the company?
- Will the system share the data with other systems or users?
d. Define Scope and Boundaries:
The designer must recognize the existence of two sets of limits:
- scope
- and boundaries.
The system's scope defines the extent of the design according to operational requirements.
Will the database design encompass the entire organization, one or more departments within the organization, or one or more functions of a single department?
Knowing the scope helps in defining the required data structures, the type and number of entities, the physical size of the database, and so on. The proposed system is also subject to limits known as boundaries, which are external to the system.
Boundaries are also imposed by existing hardware and software.
Database Modeling