A database-management system (DBMS) consists of a collection of interrelated data and a set of programs to access those data. The primary goal of the DBMS is to provide an environment that is both convenient and efficient to use in retrieving and storing database information. Thus we can say that, a database management system is a combination of hardware and software that can be used to set up and monitor a database, and can manage the updating and retrieval of database that has been stored in it.
Most DBMS have the following facilities or capabilities:
- Creating of a file, addition of data, deletion of data, modification of data; creation, addition and deletion of entire files.
- Retrieving data collectively or selectively.
- The data stored can be sorted or indexed at the user's discretion and direction.
- Various reports can be produced from the system. These may be either standardised reports or that may be specifically generated according to specific user definition.
- Mathematical functions can be performed and the data stored in the database can be manipulated with functions to perform the desired calculations.
- To maintain data integrity and database use.
- Data integrity for multiple users.
- Providing form based interface for easy accessibility and data entry.
The DBMS interprets and processes user's requests to retrieve information from a database. From the following figure we can depict that DBMS serves as an interface in several forms.
The DBMS responds to a query by invoking the appropriate subprograms, each of which performs its special function to interpret the query, or to locate the desired data in the database and present it in the desired order. Thus, the DBMS shields database users from the tedious programming they would have to do to organize data for storage, or to gain access to it once it was stored.
As already mentioned, a database consists of a group of related files of different record types, and the DBMS allows users to access data anywhere in the database without the knowledge of how data are actually organized on the storage device.
The role of the DBMS as an intermediary between the users and the database is very much like the function of a salesperson in a consumers' distributor system. A consumer specifies desired items by filling out an order form which is submitted to a salesperson at the counter. The salesperson presents the specified items to consumer after they have been retrieved from the storage room. Consumers who place orders have no idea of where and how the items are stored; they simply select the desired items from an alphabetical list in a catalogue. However, the logical order of goods in the catalogue bears no relationship to the actual physical arrangement of the inventory in the storage room. Similarly, the database user needs to know only what data he or she requires; the DBMS will take care of retrieving it.
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