DBMS

Introduction to DBMS:

The points I have learnt are:

1. What is DBMS?
2. What is need of DBMS?
3. Drawbacks of File System.
4. Advantages of DBMS over file systems.
5. Disadvantages of DBMS.
6. Application of DBMS.

What is DBMS:

Database is collection of interrelated data and management system is set of program to store and retrieve those data .

Need of DBMS:

• Developed to deal with large amount of data.
• While dealing with data , we need two optimization storage and retrieval of data.
• Main purpose of DBMS is to manage data.
• Suppose in college we have data of no of teachers, students and subject . We need system where we can add, delete, update, retrieve we need DBMS system.
• DBMS allows us to store data in such a way that this task can be performed efficiently
• Database system is much better than traditional file processing system.

Drawbacks of file system:

Traditionally we have file system for storing data. There are some drawbacks of file system:

• Data redundancy : storing same data in multiple locations.
• Data inconsistency: data redundancy leads to data inconsistency. So data become inconsistent. Eg: if age of same student is saved in many files, and it is updated in one file it may lead data inconsistency. If we try to retrieve age , we can get wrong result.
• Data isolation: No relationship exists between data.
• Dependency on application programs.
• Automicity issues: a computer system is subject to failure. In many application it ensured that once a failer has occurred the data should be stored to consistent state as it was before failure. It is difficult to ensure this property in traditional file system. Eg. Suppose transferring funds from account a to b, if failure occurs in between when fund is released from a, and before reaching b, in traditional find system you can’t restore it back to a.
• Data security : As application program are added in Adobe manner, it is difficult to enforce security constraints.

DBMS Offer solution to all these problems.

Advantages of DBMS over file system:

• No redundant data
• Data consistency and integrity
• Data security
• Privacy
• Easy access to data
• Easy recovery
• Data independency.

Disadvantages of DBMS:

• Implement cost high.
• Complexity- complex to understand than file system
• Performance - generic(all purpose efficient) so it may affect performance for some applications.