Database Management System(DBMS)

 DBMS

Introduction: A database management system (DBMS) is a collection of interrelated data and a set of programs to access those data.

The collection of data, usually referred to as the database, contains information relevant to an enterprise. 

The primary goal of a DBMS is to provide a way to store and retrieve database information that is both convenient and efficient.

The database is a collection of a large amount of data, we can define a structure for it and can manipulate it.

Database-System Applications:

DBMS has a wide variety of applications, some of these are:

  

1. Enterprise information

* sales.

* Accounting.

* Human Resources.

* Manufacturing.

* Online Retailers.

2. Banking And Finance

* Banking.

* Credit card transactions.

* Finance.

3. Universities

* Student information and grades.

4. Airlines

* The data related to customers and flights.

 

5. Telecommunication

* For keeping records of calls made, generating monthly bills, etc.

Purposes Of Database Systems

Earlier data is store in operating files and folders. It was difficult to store a large amount of data and retrieve it.

This typical File-Processing-Systems is supported by a conventional operating system.

The file-processing-system has a number of major disadvantages:

1. Data redundancy: repetition of information about the entity can not be avoided.

For example, a person having a both saving and current account in the same bank then his address and phone number are stored at two different places, so duplicate data leads to storage wastage.

2.Data inconsistency: Same data which is frequent at several places may not match after it has been updated at some places.

For example, a person wants to update the address in both accounts and during updation its only updated in the current account and not updated in the saving account so it may lead a confusion like which address gets a priority.

3. Difficulty in accessing data: when there is a large amount of data then it is difficult to fetch or access a particular data.

For example: if an admin of a bank demands the address of a customer living in the same locality then it is difficult for a manager to fetch the information about a particular customer. Either he has to do the work manually or he has to write a new program for it on hand which is going to take impractical time and cost.

4. Data isolation: since the data files are formed at different time by a different person, so structures of files generally do not match.

For example, the Address format of the saving account is Address Line1, Address Line2, city, state, pin...... and for the current account is house_no, street, locality, city,........, both have different ways of sorting so it's difficult to fetch the details of the same person in both accounts.

 

5. Integrity Problems: It is difficult to update the data according to the constraint applied.

For example, a bank has a constraint (rule) that no customer can have less than 500 in his/her account, suddenly bank updated the constraint, then it is difficult to manually change that constraint in every record.

6. Atomicity Problems: entire transaction places at once or doesn't happen at all.

7. Concurrent-access anomalies: when two users update the same data at the same time they may lead to inconsistent data.

8. Security Problems: every data has some privacy and can access by an authorized user, but in file-processing-system unauthorized users can also access the data easily, hence leads to data loss and misuse of data.

View Of Data: 

a) Data Abstraction: 

Hiding the non-essential details and showing the useful or relevant data is known as Data Abstraction.

It is classified into 3 views:

1. Physical View: it describes the physical structure like how the data is stored.

2. Logical View: describes the logical structure like data is stored in the database and what relationship exists among those data.

3. View Level: describes only the part of the entire database. The system many views for the same database.