What Do You Think About Database Design Approach?

The database should be design in this way that it will be able to meet future requirements. This evolution is possible when the designer develops a true logical model of the organization with the following characteristics: The model faithfully mirrors the operations of the organization. It is flexible enough to allow changes as new information needs arise. It supports many different user views. It is independent of physical implementation. It does not depend on the model used by a particular database management system.

A well-designed database model protects the data resource by allowing it evolve so that it serves both today's and tomorrow's information needs. If the system is truly independent of its physical implementation, it can be moved to new hardware to take advantage of technical developments. Even if the database management system chosen for implementation is replaced, the logical model of the enterprise survives. The staged design approach is a top-down method that begins with general statements of needs and progresses to more and more detail consideration of problems. Different problems are considered at different phases of the project. Each stage uses different phases of the project.

There are six phases in database design approach. Sixth phase concerns database implementation and redesign thats why I will not discuss it. These six phases are given below.

* Phase 1: Requirements Collection and Analysis
In this phase we collect information from the users and analyze the expectations of the users and intended users of the database before we design a database. This process is known as requirements collection and analysis.
* Phase 2: Conceptual Database Design

In this phase, we perform two activities. First activity or task is to design conceptual schema design by using the data requirements which we got from the first phase. This activity produces a conceptual database schema. The second activity is of transaction and application design by using the database application analyzed in phase 1.At the end of this activity we get high level specifications for these applications.
* Phase 3: Choice of a DBMS
In this face, we select DBMS which based on number of factors including technical, economic and some other factors concerned with the organization.
* Phase 4: data Model mapping or Logical database Design
In this phase, we transform the conceptual schema from high level data model used in phase 2 into the data model of chosen DBMS.
* Phase 5: Physical database Design
In this phase, we design the specifications for the stored database in terms of physical storage structures, record placement and indexes.