Database management system (DBMS) and Its architecture.

By: Rajat Kumar | Last Updated: June 05, 2018

1. Introduction:

Hello friends today we are going to discuss about data, data abstraction, database, and database management system. Data is all about information and database is managing that information for different levels. This article is for everyone who want to give some sort of IT exam, GATE exam and for technical interviews in IT companies.


2. Data:

Any kind of set of information that hold the meaning full variables, words, numbers, sentence & logic. Or

Data is a set of values of qualitative or quantitative variables. Data and information are often used interchangeably. Data can be stored in electronics physical memory.

In DBMS the smallest unit of data is called field (that stored one type of information).

Collection or set of fields called record.

Collection or set of records called file.

Collection or set of files called database.

Processed data called information.

Collection of information called knowledge.


2.1 Difference Between Data And Information:

 1.Raw facts  1.Processed data
 2. It is in unorganized form  2. It is in organized form
 3. Data doesn’t help in decision making process  3. Information helps in decision making process


3. Database management system (DBMS) Definition:

A database management system (DBMS) is a collection of interrelated data and set of information programs to access or manage those data. Or

A database management system (DBMS) is system software for creating and managing databases. The DBMS provides users and programmers with a systematic way to create, retrieve, update and manage data. Or

Another definition says that database-management system (DBMS) is a computer-software application that interacts with end-users, other applications to view database itself to capture and analyse data.

A general-purpose DBMS allows the accessing, definition, creation, querying, update, and administration of databases.




4. Database architecture (Data abstraction):

There are 3 types of levels in database architecture that shows the different type of user roles in each level.


4.1 Physical level:

How data is stored, Complex to low-level data structure. In this level data is stored in machine language (binary) or low level language into storage.

This level is complex for end user but users do not need to worry about complexity of this level because user can retrieve, insert and update database by sending query to physical level through logical level.

This level also called internal level.


4.2 Logical level:

What data is stored in the database, and what relation is exist between among them. DBA (data base administrator) uses this level for administration and to writing logics for database.

This level coordinate between user (view) level application and physical level by process commends, make logical decisions, and evaluate to move data b/w two levels.

This level also called conceptual level.


4.3 View level:

This is top level of the application user interface. The main function of this level to send the task and view the same database in different forms using different queries.

This describe only part of the entire database. This level simplifies their interaction with the system. The system may provide many views from the same database.

This level also called external or user level.


Database architecture (Data abstraction)


5. Instance and schema:

The collection of information stored in the database at a particular moment is called an instance of the database, and Overall design of the database is called the schema.

According to the level of architecture database system has several schema:

  • Physical schema: Describes database design at physical level.
  • Logical schema: Describes database design at logical level.
  • Sub-schema: Describes different views of database.


That’s it for today in upcoming articles we will be going to discuss different type of topics like: database models, database schemas, and database relation algebra.