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Database management systems is a system software component that is generally purchased and installed separately from other system software component (e.g. Operating systems) include; Microsoft Access, Oracle etc.

A DBMS has 4 key components:

 Application Program Interface (API)
 Query interface
 Administrative interface
 Set of data access programs and subroutines


There are three main features of a database management system that make it attractive to use a DBMS in preference to other systems. These features are:
• Centralized data management,
• Data independence
• Systems integration.
In a database system, the data is managed by the DBMS and all access to the data is through the DBMS providing a key to effective data processing. This contrasts with conventional data processing systems where each application program has direct access to the data it reads or manipulates.
In the conventional data processing application programs, the programs usually are based on a considerable knowledge of data structure and format. In such environment any change of data structure or format would require appropriate changes to the application programs. If major changes were to be made to the data, the application programs may need to be rewritten.
In a database system, the database management system provides the interface between the application programs and the data. When changes are made to the data representation, the metadata maintained by the DBMS is changed but the DBMS continues to provide data to application programs in the previously used way. The DBMS handles the task of transformation of data wherever necessary.
This independence between the programs and the data is called data independence. Data independence is important because every time some change needs to be made to the data structure, the programs that...