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DBMS Functions

A DBMS performs several important functions that guarantee the integrity and consistency of the data in the database. Most of those functions are transparent to end users, and most can be achieved only through the use of a DBMS.

Data Dictionary Management

The DBMS stores definitions of the data elements and their relationships (metadata) in a data dictionary. In turn, all programs that access the data in the database work through the DBMS. The DBMS uses the data dictionary to look up the required data component structures relationships, thus relieving you from having to code such complex relationships in each program. Additionally any modifications made in a database structure are automatically recorded in the data dictionary, thereby freeing you from having to modify all of the programs that access the changed structure. In other words, the DBMS provides data abstraction and it eradicates structural and data dependency from the system.


Data Storage Management

The DBMS creates and manages the complex structures required for data storage, thus relieving you from the difficult task of defining and programming the physical data characteristics. A modern DBMS system provides storage not for only the data, but also for related data entry forms or screen definitions, report definitions, data validation rules.

            Data storage management is also important for database performance tuning. Performance tuning relates to the activities that make the database perform more efficiently in terms of storage and access speed.

Data Transformation and Presentation

The DBMS transforms entered data to conform to required data structures. The DBMS relieves you of the chore of making a distinction between the logical data format and physical data format. That is, the DBMS formats the physically retrieved data to make it conform to the user’s logical expectations. For example, imagine an enterprise database used by a multinational company. An end user in England would expect to enter data such as April 12, 2010 as “12/04/2010”. In contrast, the same date would be entered in the United States as “04/12/2010”. Regardless of the data presentation format, the DBMS must manage the date in the proper format for each country.

Security Management

The DBMS creates a security system that enforces user security and data privacy. Security rules determine which users can access the database, which data items each user can access, and which data operations (read, add, delete, or modify) the user can perform. This is especially important in multiuser database systems where many users access the database simultaneously.

Multiuser Access Control

To provide data integrity and data consistency, the DBMS uses sophisticated algorithms to ensure that multiple users can access the database concurrently without comprising the integrity of the database. e.g., two friends can access the bank’s ATM at the same time.

Backup and Recovery Management

The DBMS provides backup and data recovery to ensure data safety and integrity. Current DBMS systems provide special utilities that allow the DBA to perform routine and special backup and restore procedures. Recovery management deals with the recovery of the database after a failure, such as bad sector in the disk or a power failure. For example, backup means you had made another copy of your notebook so whenever your notebook get lost you can use your backup (means another notebook), and recovery means after getting lost your notebook, by luck you got back.

Data Integrity Management

The DBMS promotes and enforces integrity rules, thus minimizing data redundancy and maximizing data consistency. The data relationships stored in the data dictionary are used to enforce data integrity. Ensuring data integrity is especially important in transaction-oriented database systems.

Database Communication Interfaces

Current-generation DBMSs accept end-user requests via multiple, different network environments. For example, the DBMS might provide access to the database via the Internet through the use of Web browsers such as Internet explorer. In this environment, communications can be accomplished in several ways:

·         End users can generate answers to queries by filling in screen forms through their preferred web browser.
·         The DBMS can automatically publish predefined reports on a web site.
·         The DBMS can connect to third-party systems to distribute information via-email or other productivity applications.

Database Access Language and Application Programmers

The DBMS provides data access through a query language. A query language is a non-procedural language-one that lets the user specify what must be done without specifying how it is to be done. 



Resource Used: 

1. Database Management System (By: Peter Rob) 

Compiled By: Chaudhary Amit V.
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