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Thursday, March 11, 2010

Learn DBMS

DBMS stands for Database Management System. A DBMS consists of collection of interrelated data and a set of program to access that data. The collection of data is known as a database. A database consists of the data relat ed to one organization. Prior to DBMS systems, the data was kept under the file system in forms of multiple files. The following are the disadvantages of the File system:-


1. Difficulty in Accessing data:- In the file system it is very difficult to find the data which is needed for some specific purpose. Like to get the average sale of the quarter needs to process all files for the quarter and then do some processing.

2. Data inconsistency and redundancy:- As the files and processing systems created by different vendors and programmers, so there is a inconsistency of data as different people prefer the different style of data handling. Also the different systems may use the different programming languages to develop the processing systems so the multiple copies of the same file kept under various places so redundancy is another problem we have with file system.

3. Security Problem:- There is a great risk of unauthroized person access the file system and get the data. So security is the major concern in the file system.
4. Integrity Problem:- The integrity issue is also a major concern as the data stored in the file can be changed easily. While creating files there is no specific rules checked while storing the data.

Advantages of Database Management System:-

The following are the advantages of DBMS systems:-


1. A data can be validated before storing into the DBMS system.These rules for data validation are known as Constraints in DBMS.

2. Different users can be created with different rights for the database.So DBMS systems are more secure than the conventional file system.

3. The relationships of the data can also be stored along with the data which is not possible for the files.

4. A simple english like language SQL is introduced which helps to access data more efficiently and quickly.

5. Multiple users can access the data simultenously and DBMS system will take care the conflicts.

6. The dependent tasks can be controlled with transaction management facility of the DBMS.

For example:- Transfering the cash from one account to second account consits of withdrawing the amount from one account and deposit in other. What if the application fails after the withdrawl so DBMS system will rollback the withdrawl automatically

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