Last minute notes

 Database Management System

Before we go through the definitions, concepts, characteristics of DBMS first let us understand a few basics:-

What is Data?

We are very familiar with the term data as it is used widely in various fields. So, what is data,

● Data is nothing but the raw facts and figures.

● Data is individual facts, statistics, or items of information.

● Data is a set of values of qualitative or quantitative variables about one or more persons or objects.

What is Database?

The database is a collection of interrelated data which is used to retrieve, insert and delete the data efficiently. It is also used to organize the data in the form of a table, schema, views, and reports, etc.

For instance: The college Database organizes the data about the admin, staff, students and faculty etc.

Using the query processing language in the database, you can easily retrieve, insert, and delete the information.

Note:- The SQL is used for relational databases whereas NoSQL is used for non relational or distributed databases.

What is a Database Management System?

Database Management System (DBMS) is a software for storing and retrieving users' data while considering appropriate security measures. It consists of a group of programs which manipulate the database. The DBMS accepts the request for data from an application and instructs the operating system to provide the specific data. In large systems, a DBMS helps users and other third-party software to store and retrieve data.

It provides protection and security to the database. In the case of multiple users, it also maintains data consistency.

DBMS allows following features:

● Data Definition: It is used for creation, modification, and removal of definition that defines the organization of data in the database.

● Data Update: It is used for the insertion, modification, and deletion of the actual data in the database.

● Data Retrieval: It is used to retrieve the data from the database which can be used by applications for various purposes.

● User Administration: It is used for registering and monitoring users, maintaining data integrity, enforcing data security, dealing with concurrency control, monitoring performance and recovering information corrupted by unexpected failure.

What are the characteristics of DBMS?

● DBMS provides security and avoids redundancy.

● It supports the manipulation and processing of the data.

● Supports multiple transaction processing and sharing of the data.

● It supports the ACID properties that help maintain the data in a healthy state in case of failure.

● It supports the reduction of complex relationships between data.

What are the advantages of DBMS over file systems?

● Controls database redundancy: The redundancy in the database is controlled by normalization of the database.

● Provides security: The limited access to the data makes the database much more secure than the file system.

● Backup: The DBMS provides the backup feature which helps retrieving the data in case of failure.

● Consistency and Integrity: The ACID properties help the database maintain consistency and integrity by applying multiple constraints.

● Time Saving: It takes less development time and maintenance.

● Supports Concurrency: A DBMS schedules concurrent access to the data in such a manner that only one user can access the same data at a time

What are the disadvantages of DBMS?

● Cost: The cost of hardware and software is high.

● Need for training: Most of the databases are complex which requires training.

● Size: It requires large memory and disk spaces to run them efficiently.

● High impact of failure: In some organizations the data stored in a single database and if the electrical failure occurs or somehow database gets damaged the data is lost with no backup method.