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Friday, 30 September 2011

Components of DBMS


Components of DBMS

The following  are the five components of a DBMS
  •   Hardware                                                                                                                                 Can range from a PC to a network of computers. 
  • Software
         DBMS, operating system, network software (if necessary) and also the application programs. 
  • Database                                                                                                                                        It maintains , manipulate and organisethe entire database of the organisation. 
  • Procedures                                                                                                                                       Instructions and rules that should be applied to the design and use of the database and DBMS. The set of rules and relationship that defines and governs the interaction among element of the database. 
  • People
           At least one person who “owns” and is responsible for the database.
        Includes database designers, DBAs, application programmers, and end-users

Objectives Of DBMS



Objectives of DBMS

The objectives that the management should keep in mind when they design and organize their data base management systems are:
(i) Provide for mass storage of relevant data,
(ii) Make access to the data easy for the user,
(iii) Provide prompt response to user requests for data,
(iv) Make the latest modifications to the database available immediately,
(v) Eliminate redundant data,
(vi) Allow for multiple users to be active at one time,
(vii) Allow for growth in the database system,
(viii) Protect the data from physical harm and unauthorised access.
 A database is a collection of data organised to serve many applications efficiently by centralising the data and minimising redundant data. A database is a collection of data organised to service many applications at the same time by storing and managing data so that they appear to be in one location.
 When an organisation has a centrally controlled, integrated collection of logically organised data, it has a database. If the collection of data does not respond to command and queries from a central control point, it is not single database; similarly for the part of the definition that calls for integration. The various pieces of data within the database must have some logical connections or relationships among themselves for the database to be integrated. Eg: Inventory control and production planning data are closely related and when put into one database, are a prime example of integration. And finally, logical organisation is required that is, the data elements must be in specific places and bear specific relationships to each' other for the collection of data to be a substantial database.
DBMS is a collection of programs that enable users to create and - maintain a database. The DBMS is hence a general purpose software system that facilitates the processes of defining, constructing and manipulating databases for various applications.

Defining database involves specifying the data type structures and constraints for the data to be stored in the database. Constructing the database is the process of storing the database itself on the storage medium that is controlled by DBMS. Manipulating includes such functions as merging the database to reflect changes in the miniworld and generating reports from the data.
The concept of a database is that data needs to be managed in order to be available for processing and have appropriate quality. This data management includes both software and organisation, the software to create and manage a data base is a database management system. This system, or set of rules and methods, allows for the definition, creation, updating, reading, maintenance and protection of the database. In short, this system is a database management system.
DBMS consists of a collection of inter-related data and a set of programs to access that
data. The collection data is usually referred to as database which contains information about one particular enterprise. The primary goal of a DBMS is to provide an environment that is both convenient and efficient to use in retrieving and storing database information. The DBMS is the interface between the user of application programs on one hand and the database on the other.
 

A DBMS provides a secure and survivable medium for the storage and retrieval of data.
If the users and applications do not share data among themselves and if the longevity of the data is only till the end of the process or application that created it, then there is not much need for a DBMS. But in real world, the data is shared and is persistent (that is, the data has a life beyond the boundaries of the programs and applications that created it). Also, the real world data have a structure. It is related to one another and has constraints. These features are well represented and can be efficiently managed using a DBMS.        Also, the different users of the data need to create, access and
manipulate the data. The DBMS provides mechanisms to achieve these objectives without compromising the security and integrity of the data. Therefore, if the data is shared, if it is persistent, if the users want it be secure and easy to access and manipulate, then use of a database management system is the best available alternative