INTRODUCTION TO Database Management System and Relational Database Management System

A DBMS (Database Management System) is a software program used to manage a database. These programs enable users to access and modify databases. It basically controls the storage management and fetching of data from the database.

A DBMS includes four main components, which are:
-Modeling Language,
-Data Structures,
-DB Query Language and Report Writer,
-Transaction Mechanism.

RDBMS
RDBMS is a relational database management system. Basically, we can say that RDBMS is an extension of DBMS systems.

Difference between DBMS and RDBMS

1. RDBMS (Relational database management system) applications store data in a tabular form while DBMS applications store data as files.

2. Normalization is added to RDBMS whereas not present in the DBMS system.

3. RDBMS maintains a relationship between tables ( Primary Key or Foreign Key constraints) but in DBMS is not maintained.

4. RDBMS supports ACID properties of Transactions (Atomicity, Consistency, Isolation, and Durability) but DBMS does not.

5. RDBMS supports distributed databases but DBMS does not.

6. Examples of RDBMS are MySQL, Postgres, SQL server, oracle, etc and DBMSs are file systems, XML, Dbase, Microsoft Access, LibreOffice Base, FoxPro, etc,

TYPES OF LANGUAGE:

DDL – DATA DEFINITION LANGUAGE
The SQL sentences that are used to create these objects are called DDL’s or Data Definition Language. The SQL provides various commands for defining relation schemas, deleting relations, creating indexes and modify relation schemas. DDL is part of SQL which helps a user in defining the data structures into the database. Following are the various DDL commands are
• Alter table & Create table & drop table
• Create index & drop index
• Create view & drop view

DML – DATA MANIPULATION LANGUAGE
The SQL sentences used to manipulate data within these objects are called DMLs or Data Manipulation Language. It is a language that enables users to access or manipulate data as organized by appropriate data models. Through data manipulation, we have:
• Retrieval of information stored in a database.
• Insertion of new information into the database.
• Deletion of information from the database.
• Modification of data stored in a database.

THE FOLLOWING DML COMMANDS ARE:
• Select
• Update
• Delete
• Insert

DCL – DATA CONTROL LANGUAGE
The SQL sentences, which are used to control the behavior of these objects, are called DCLs or Data Control Language. It is the language used to control data and access to the database. Following are some DCL commands are
• Commit
• Rollback
• Savepoint
• Set transaction

A Data Control Language (DCL) is a computer language and a subset of SQL, used to control access to data in a database.
Examples of DCL commands include:
• GRANT to allow specified users to perform specified tasks.
• REVOKE to cancel previously granted or denied permissions.

The following privileges can be GRANTED TO or REVOKED FROM a user or role:
• CONNECT
• SELECT
• INSERT
• UPDATE
• DELETE
• EXECUTE
• USAGE