Database & Database Management System (DBMS)

Database Systems Design, Implementation, and Management, 6e
Chapter 1: Database Systems

ISBN: 061921323X Author: Peter Rob, Carlos M. Coronel
copyright © 2005 Course Technology

1.2 Introducing the Database and the DBMS

Efficient data management typically requires the use of a computer database. A database is a shared, integrated computer structure that houses a collection of:

* End user data, that is, raw facts of interest to the end user.
* Metadata, or data about data, through which the data are integrated and managed.

The metadata provide a description of the data characteristics and the set of relationships that link the data found within the database. In a sense, a database resembles a very well-organized electronic filing cabinet in which powerful software, known as a database management system, helps manage the cabinet’s contents. A database management system (DBMS) is a collection of programs that manages the database structure and controls access to the data stored in the database. The DBMS makes it possible to share the data in the database among multiple applications or users.

Because data are the crucial raw material from which information is derived, in our information-based society we must have a good way of managing such data. As you will discover in this book, the DBMS helps make data management much more efficient and effective. The following points are worth stressing:

* The DBMS helps create an environment in which end users have better access to more and better-managed data than they did before the DBMS became the data management standard. Such access makes it possible for end users to respond quickly to changes in their environment. The availability of data, combined with the tools that transform data into usable information, empowers end users to make quick, informed decisions that can make the difference between success and failure in the global economy.
* Wider access to well-managed data promotes an integrated view of the organization’s operations and a clearer view of the “big picture.” It becomes much easier to see how actions in one segment of the company affect other segments.
* The probability of data inconsistency is greatly reduced in a properly designed database that is managed through a DBMS. Better data make it possible to generate better information, on which better decisions are based.
* The DBMS makes it possible to produce quick answers to ad hoc queries. (A query is a question, and an ad hoc query is a spur-of-the-moment question.) For example, end users, when dealing with large amounts of sales data, might want quick answers to questions (ad hoc queries) such as:
o What was the dollar volume of sales by product during the past six months?
o What is the sales bonus figure for each of our salespeople during the past three months?
o How many of our customers have credit balances of $3,000 or more?

The advantages of using a DBMS are not limited to the few we have just listed. In fact, you will discover many more advantages as you learn more about the technical details of databases and their proper design.

Figure 1.2 illustrates that the DBMS serves as the intermediary between the user and the database by translating user requests into the complex code required to fulfill those requests. The DBMS hides much of the database’s internal complexity from the application programs that use the database. The application program might be written by a programmer using a programming language such as COBOL, Visual Basic, or C++, or it might be created through a DBMS utility program.

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