Database Management System (DBMS)
A database management system (DBMS) is a set of programs that allow users to Create, maintain and manipulate database, and store or retrieve data from those database files. It provides user-friendly access and controls between user and database. Its main purpose is to improve data sharing, data access, decision making and increase end user productivity.
Manipulation of data includes the following.
• Adding new data, for example adding details of new student.
• Deleting unwanted data, for example deleting the details of students who have Completed Course.
• Changing existing data, for example modifying the fee paid by the student.
The DBMS helps to create an environment in which users have better access to data. DBMS helps to give an integrated view of the organization’s operations. The DBMS makes it possible to share the data in the database among multiple applications and users.
Some examples of the database systems managed by DBMS are:
o Customer information system o inventory information o Library management o Accounting and bookkeeping
Examples of DBMS include Microsoft Access, Microsoft SQL Server, Sybase, Oracle, MySQL, etc.
Advantages Of DBMS Over File Management System:-
DBMS has many advantages over the file management system because it provides solutions to all the problems faced in file management system. The following problems were faced in file management system. Reduced Data Redundancy: Data redundancy is the duplication of data in many different files in file management system. For example, a salesman’s data may be held on a file in the Sales Department and also Personnel Department. When data is to be updated, it must be changed in both files. This results in wastage of storage space and may lead to data inconsistency.
This problem is not faced in DBMS because all the data belonging to the entire organization is centralized in a common pool of data, accessible by all the programs.
Data consistency: in file management system, same data may be held in several different files, has to be updated in each separate file when it changes. If data is not updated in any file it uses data inconsistency.
This problem is solved in DBMS because all the data is centralized for use by all the programs. For example, in a School, students’ information such as name, address, phone number and class are held in a file in Admission Office. The same data With tuition fee and Some her data is also kept in another file in Accounts Office. If a student’s address changes it must be updated on both files. In case it is updated in only one file, the other file will have out-of-date data. This will cause data inconsistency.
Program-Data Dependency: In file management system, every computer program in each department has to specify exactly what data fields constitute a record. Any change to the format of the data field of a record, such as adding a new field or changing the length of a field means that every program which uses that file has to be changed. For example, if a new field, place of birth of students is to be added in student data files in Admission Office and Accounts Office, then both the programs need to be changed.
Lack of Flexibility: In file management System, when information of a non-routine nature is needed, it can take Weeks to assemble the data from the various files and write new programs to produce the required reports. For example, a report about students is required in a school that has to merge information stored in various files. This will require lot of time and effort by the programmer to Write a program to print such a report in file management system whereas it can be very easily produced in database management system.
Data not Sharable: When a copy of a data file is made for sharing data with other people in a file management system, it will soon lead to data inconsistency if data in one of the files is not updated. Therefore, it is difficult to share data with others in a file management system.
Backup and Recovery: DBMS provides facilities for backup and recovery from failures including disk crash, power failure, software errors, which may bring the database from the inconsistent state to a state prior to the failure. Data Security: in Conventional filing systems there is no centralized security system which restricts users according to their role in the organization. DBMS makes it easier to enforce Security restrictions since database is Centralized. Users are provided permissions to access data according to their rights.