Database management system

Database Management System (DBMS) is a software system that enables users to define, create, maintain and control access to the database. It acts as an interface between the database and the users ensuring that data is consistently organized and remains easily accessible.

Overview

A Database Management System (DBMS) is a software package designed to define, manipulate, retrieve and manage data in a database. A DBMS generally manipulates the data itself, the data format, field names, record structure and file structure. It also defines rules to validate and manipulate this data.

Types of DBMS

There are four major types of DBMS:

1. Relational database management system (RDBMS): This is the most common DBMS type in the market. Examples include MySQL, Oracle, and Microsoft SQL Server. RDBMS is based on the relational model, which stores data in the form of rows and columns and uses Structured Query Language (SQL) for database access.
2. Hierarchical DBMS: This type of DBMS employs the "parent-child" relationship of storing data. Its structure is like a tree with nodes representing records and branches representing fields. The windows registry used in Windows XP is an example of a hierarchical database.
3. Network DBMS: This type of DBMS supports many-to-many relations. This usually results in complex database structures. RDM Server is an example of a database management system that implements the network model.
4. Object-oriented DBMS: This type supports the storage of new data types. The data can be presented in the form of objects, as in programming languages like C++, Java, .NET, etc.

Functions of DBMS

A DBMS has several functions that can be defined through the following functionalities:

1. Data Definition Language (DDL): It allows a database administrator to create and modify the structure of database objects in the database.
2. Data Manipulation Language (DML): This is used to access, modify or retrieve the database data.
3. Data Control Language (DCL): This includes commands such as GRANT and REVOKE which mainly deals with the rights, permissions and other controls of the database system.
4. Transaction Control Language (TCL): This deals with the transaction within the database.

Advantages of DBMS

The advantages of DBMS are:

1. Data Independence: The data is held separate from the applications that are used to manage the data.
2. Efficient Data Access: DBMS utilizes a variety of sophisticated techniques to store and retrieve data efficiently.
3. Data Integrity and Security: DBMS provides mechanisms to enforce user-defined integrity constraints and also provides a security system that can be used to control access to the database at different levels.
4. Data Administration: DBMS provides a central store of data that can be accessed by multiple users in a controlled manner.

Disadvantages of DBMS

The disadvantages of DBMS are:

1. Complexity: The provision of the functionality that is expected of a good DBMS makes the DBMS an extremely complex piece of software.
2. Size: The functionality provided by DBMS requires a large amount of disk space, large amounts of memory and a fast processor.
3. Cost of Hardware and Software: A significant cost of purchasing and maintaining the DBMS.

See Also

• Database
• Data Management
• Data Warehousing
• Data Mining

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