Summary of Database Management Systems.

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Summary

This chapter examined the database approach to data manag ment and showed how this approach enables business organ zations to overcome data redundancy and the associated problems that plague the flat-file approach to data management. It showed that the database concept is composed of four dynamically interrelated components: users, the database management system, the database administrator, and the physical database. The DBMS stands between the physical database and the user community. Its principal function is to provide a controlled and secure environment for the database. This is achieved through software modules, such as a query language, a data definition language, and a data manipulation language. The DBMS also provides security against human error and natural disaster through various backup and recovery modules.

Database models are abstract representations of data about entities, events, and activities, and their relationships within an organization. The focus of attention was on the relational model. A number of database design topics were covered, including data modeling, the creation of user views from ER diagrams, and data normalization techniques. Finally, the chapter presented a number of issues associated with distributed databases. It examined three possible database configurations in a distributed environment: centralized, partitioned, and the replicated databases.

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