Database Management System Basic Concepts By Sumit Singh

Data Base Management System

DBMS A data base management system is the software system that allows users to define, create and maintain a data and provides controlled access to the data.

A database management system (DBMS) is basically a collection of programs that enables users to store, modify, and extract information from a database as per the requirements. DBMS is an intermediate layer between programs and the data. Programs access the DBMS, which then accesses the data. There are different types of DBMS ranging from small systems that run on personal computers to huge systems that run on mainframes.

The following are examples are main examples of database applications:

• Computerized library systems
• Automated teller machines
• Flight reservation systems
• Computerized parts inventory systems

A database management system is a piece of software that provides services for accessing a database, while maintain all the required features of the data. Commercially available Database management systems in the market are dbase, FoxPro, IMS and Oracle.
These systems allow users to create, update, and extract information from their database. Compared to a manual filing system, the biggest advantages to a computerized database system are speed, accuracy and accessibility.

Components of the DBMS Environment

There are five major components in the DBMS environment

- Hardware
- Software
- Data
- Users
- Procedures

1. Hardware: - The hardware is the actual computer system used for keeping and accessing the database. Conventional DBMS hardware consists of secondary devices, usually hard disks, on which the database physically resides, together with the associated input-output devices controllers and so forth. Database run on range of machines, from Micro-computer to large mainframes. Other hardware issues for a DBMS includes database machines, which is hardware designed specially to support a database system.

2. Software: - The software is the actual DBMS. Between the physical databases itself and the users of the system of software, usually called the Database Management System or DBMS. All requests from users for access to the database are handled by the DBMS. One general function provided by the DBMS is thus the shielding of database from complex hardware-level detail.
The DBMS allows the users to communicate with the database. In a sense, it is the mediator between the database and the users. The DBMS controls the access and helps to maintain the consistency of the data. Utilities are usually included as part of the DBMS. Some of the most common utilities are writers, application development tools and other design aids.

3. Data: - It is the most important component of DBMS environment from the end users point of view. The database contains operational data and the meta-data, the “data about data”.
The database should contain all the data needed by the organization. In of the major features of databases is that the actual data are separated from the programs that use the data. A database should always be designed, built and populated for a particular audience and for a specific purpose.

4. Users: - there are a number of users who can access or retrieve data on demand using the application capacities. The users of a database system can be classified in the following groups, depending on their degrees of expertise or the mode of their interactions with DBMS. The users can be:

• Naive Users
• Online Users
• Application Programmers
• Sophisticated users
• DBA

5. Procedures: - procedures refer to the instructions and rules that govern the design and use of the database. The users of the system and the staff that manage the database require documented procedures on how to use or run the system.
These may consist of instruction on how to:

- Log onto the DBMS
- Use a particular DBMS facility or application program
- Start and stop the DBMS
- Make backup copies of the database
- Handle hardware or software failures
- Change the structure of a table, reorganize the database across multiple disks, improve performance, or archive data to secondary storage.