WHAT IS A DATABASE MANAGEMENT SYSTEM (DBMS)
WHAT IS A DATABASE MANAGEMENT SYSTEM (DBMS)
The DBMS is software designed to manage and maintain the database of an organization. The main steps are data structuring, defining, integrating, updating and creating. Through these steps, it manipulates the data and provides an environment which is appropriate to use in retrieving and storing the database information.
The DBMS is a collection of the interrelated files and a set of programs through which the users can access and modify their files. DBMS is software that facilitates flexible management of data. It is generally composed of three sub-systems which are described as follows:
1. Database definition: in this sub-system, the complete database is described with the help of a special language known as the Data Description Language (DDL). However, in the case of the database in different files, one file at a time may be defined as that would give maximum flexibility.
2. Database manipulation: after the database is defined, elements of data can be stored. The stored data may either be retrieved or updated later through data manipulation language (DML). The manipulation sub-system can retrieve the required elements of data in a variety of sequences.
3. Database support: this sub-system performs database utility or service functions that include functions like list files, change file passwords, change file capacities, print file statistics, unlock files, etc.
In DBMS performs a wide variety of functions, which are discussed as follows:
1. Data organization: DBMS organizes data items as per DDL. Database administrator decides about the data specification that are most suited to top each application.
2. Data integration: data is inter-related together at the element level and can be manipulated in many combinations during the execution of a particular application program. DBMS facilitates the collection, combination, and retrieval of the required data to the user.
3. Physical/logical level separation: DBMS separates the logical description and relationships of data from the way in which the data is physically stored. It also separates out the application, programs, and their associated data. This adds data insecurity in view of the data access by different programs that describe data in different ways.
4. Data control: DBMS receives requests for storing data from different programs. It controls how and where data is physically stored. Similarly, it locates and returns requested data to the programs.
5. Data protection: data protection and security are one of the major concerns in a database. DBMS protects the data against access by unauthorized users, physical damage, and operating system failure, simultaneous updating, etc. it also protects and secures the content of a database as well as the relationships of data elements. DBMS is equipped with a facility to backup data and restore it automatically in the case of any system failure. Concurrent access control is ensured by the provision of ‘locks’. Other security features implemented in the system include password protection and sophisticated encryption schemes.
6. Data stores: the data are stored in a database in a particular manner. The user of the database needs not to know how the data are actually stored.
7. Data definition and data directory: since the data independence is provided to the user, it requires that all the users understand the data in the same manner. Therefore, each data entity is defined in the system and its directory is formed for all the users.
8. Interrogation: in interrogation, the data are selected from the database and extracted or copied for processing. For interrogation, it is necessary to identify the data or a part of the data and then through the use of query language the information is processed and printed.
9. Updating: the database needs updating as the value of the data keeps changing from time to time. The updates are made by processing the transaction data against the data in the database.
10. Creation: initially, the database is to be created in the manner and the kind as defined in the DBMS. The data is entered into the database by the transaction processing. A special program is written to create the database. The DBMS organizes the data internally in the structure defined in the DBMS.
