Introduction to Design Process
Design of the Database Schema, design of the programs that access and update the data, design of a security scheme for controlling access to the data are all involved in the creation of a Database. The central role in the designing process involves the requirements of the user.
For designing a database, there are four phases, namely:
- Initial Phase : The Initial Phase of database design is to fully describe the data needs of the potential database users.
- Conceptual Design Phase : The designer chooses a data model, by applying the concepts of the data model that is chosen and translates these requirements into a conceptual schema of the database.
A fully developed conceptual schema indicates the functional needs of the user. Here, the users describe various operations that have to be performed on the data.
The operations can include updating, searching, retrieving and deleting data.
- Logical Design Phase : The database designer plots the high-level conceptual schema onto the implementation of the data model of the database system that has to be used.
The implementation data model is also called the relational data model.
- Physical Design Phase : Here, the designer uses the resulting system-specific database schema. In this phase, the physical features of the database are specified.
The following two issues are to be avoided In designing a database schema,
- Redundancy
- Incompleteness