Explain the concept of Database Management System. Describe the types of DBMS and write SQL commands for data manipulation.

A Database Management System (DBMS) is software that provides an interface for users and applications to interact with databases. It manages data storage, retrieval, updating, and administration.

Types of DBMS:

1. Hierarchical DBMS — Data organized in tree-like structure with parent-child relationships. Example: IBM IMS.
2. Network DBMS — Extension of hierarchical, allows many-to-many relationships. Example: Integrated Data Store (IDS).
3. Relational DBMS (RDBMS) — Data stored in tables (relations) with rows and columns. Most widely used. Example: MySQL, PostgreSQL, Oracle.
4. Object-Oriented DBMS — Data stored as objects, similar to OOP. Example: db4o, ObjectDB.

SQL Commands for Data Manipulation (DML):

• SELECT — Retrieve data:

SELECT Name, Salary FROM Employee WHERE Department = 'IT';

• INSERT — Add new records:

INSERT INTO Employee (EmpID, Name, Department) VALUES (1, 'Sita Thapa', 'HR');

• UPDATE — Modify existing records:

UPDATE Employee SET Salary = 55000 WHERE EmpID = 1;

• DELETE — Remove records:

DELETE FROM Employee WHERE EmpID = 5;