Database Management System
Typically database management system is considered as an electronically and computerized record keeping system. However, DBMS is a collection of program, which are used to define, create and maintain database. Basically, DBMS is a general purpose software package whose overall purpose software package whose overall purpose is to create and maintain information and to make information available on demand.
There are many functions of general purpose DBMS software but the main function are
(I) Defining the Structure of Database
It involves defining table, fields and their data types, constraints for data to be stored in the database, and their relationship among the tables.
(II) Population the Database:
It involves storing data into database.
(III) Manipulating the Database:
It involves to retrieve the specific data, update data, delete data, insert new data and to generate reports.
Components of Database Management System
A database management system consists of several components. Each component plays a very important role in DBMS.
The major components are
- Database Access Language
The main component of DBMS is the software. It is a set of programs used to handle the database and to control and manage the overall computerized database system.
This may include
- DBMS software, which is the most important software component in the overall system.
- Operating system including network software being used in the network, to share the data of database among multiple users.
- Application programs must be developed in the programming languages such as C++, Visual Basic that are used to access database in DBMS to perform different operations on database. Now-a-day most of the modern application programs are online, developed by using ASP or JSP technology.
- Others include application development tools, report writes and so on.
Hardware consist of a set of physically and electronic devices such as computers (together with associated I\O devices like disk), storage devices, I/O channels, electromechanical devices that make interface between computers and the real world system etc., and so on. It is impossible to implement the DBMS without any kind of hardware devices.
Data is the most important component of the DBMS environment. In DBMS, the databases are defined, constructed and then data is stored, update and retrieved to and from the databases. The database contains both actual (or operational) data and metadata (data about data).
The data in database is integrated and can be joined together to generate complicated reports. Data can also be easily shared among different users. The data integration and the data sharing provide the major advantages of a database system.
- Data Integration
It means that the data in database is stored in compatible formats and logical relations among them are also created.
- Data Sharing
It means that individual pieces of data in the database can be shared among different users. Each of those can have access to the same piece of data at the same time and different users can use it for different purposes.
Procedure refers to the instruction and rules to design the database and to use the DBMS. The users who operate and manage the DBMS require document procedure to use or run the DBMS.
5) Database Access Language
The database access language is used to communicate or to access the data to or from the database. The user use to access the database access language to enter new data, change the existing data in database and retrieve required data from database. The user writes a set of appropriate command in a database access language and submits these to the DBMS. The DBMS translate the user’s commands and sends it to a specific part of the DBMS called the Database Engine. A database engine always generates a set of results according to the commands submitted by users, converts these into a user readable form called Inquiry Report and display on screen.
The most popular database access language is SQL (Structured Query Language). Relational Databases are must be required to have a database query language. Today most of the Relational Database Management Systems use SQL as database access language.
Users are the people who manage the database and perform different operations on the database in the database system.
There are three types of people which perform different roles in database system. These are
- Application Programmers
- Database Administrators
The people who writes application programs in programming language (such as Visual Basic, Java, or C++) to interact with database are called Application Programmers. The end-users use the application program written by application programmer.
A person who is responsible for managing and controlling the overall database management system is called database administrator or simply DBA. A database administrator shares the following responsibilities.
- Installing and managing the DBMS.
- Creating the DB and related objects like tables and indexes etc.
- Authorizing access to the data.
- Coordinating and monitoring DBMS.
- Acquiring software and hardware resources as needed.
- Security and integrity control.
- Creating backup of data regularly.
The end-users are the people who interact with DBMS to perform different operations on database such as retrieving, updating, inserting, deleting data etc. for retrieving the useful information. The end-user access the DBMS through application programs interface, IDE provided by DBMS or SQL interface. The interface is provided as an integral part of DBMS.