Database Design

Database Design

Databases are intended for a variety of users, often running different applications. This sets high requirements on the organization of the data in the databases. Quite different queries must be handled efficiently. Efficiency aside, it must be possible to formulate such queries. The database must be organized in a manner that allows the users to store, update, and query the data they desire, without posing restrictions other than those necessary for maintaining the consistency of the data. The task of database design is to achieve this goal.

Information systems design is usually based on either the data-driven or the function-driven approach. In the data-driven approach the emphasis is in finding out what data has to be stored and manipulated in the system. The function-driven approach puts emphasis on the applications that the system has to support.

Phases of database design

It has become a standard to divide the database design process into four phases: requirement analysis, conceptual design, logical design, and physical design.

Requirements analysis

The requirement analysis produces an operationally-oriented description of the database. Its purpose is to ensure that the database contains the data necessary for the functions and applications where the database is used. The requirements analysis should be done mainly by the database designer who interviews the users to find out their needs. Participatory design is a more modern approach where the users and designers together construct a description of the database and its usage. This approach has been made possible by the development of more intuitive modeling techniques and tools that support their use.

Conceptual design

The conceptual design produces a description of the database using some conceptual data model. The purpose is to describe the structure of the data in high-level terms. The resulting description of the database is called a database schema. The main task to conceptual design is...