docs: Add structured DBMS notes — Shiwans

DBMS/DBMS Structured Notes/01_Introduction.md

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+# Introduction to DBMS
+
+## What is a DBMS?
+- DBMS stands for **Database Management System**.
+- It is software that allows users to create, manage, and manipulate databases.
+- Example: MySQL, Oracle, PostgreSQL, MongoDB.
+
+## Why do we need DBMS?
+- To store data efficiently.
+- To ensure data consistency and security.
+- To provide easy access and sharing of data among multiple users.

DBMS/DBMS Structured Notes/02_Types_of_DBMS.md

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+# Types of DBMS
+
+1. **Hierarchical DBMS**
+   - Data is organized in a tree-like structure.
+   - Parent-child relationship.
+   - Example: IBM Information Management System (IMS).
+
+2. **Network DBMS**
+   - Uses a graph structure with nodes and edges.
+   - Allows many-to-many relationships.
+
+3. **Relational DBMS (RDBMS)**
+   - Data is stored in **tables (relations)**.
+   - Uses SQL to interact with data.
+   - Example: MySQL, PostgreSQL, Oracle.
+
+4. **Object-oriented DBMS**
+   - Stores data as objects (similar to OOP).
+   - Supports complex data types like multimedia.

DBMS/DBMS Structured Notes/03_Key_concepts.md

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+# Key Concepts in DBMS
+
+- **Table**: A collection of rows and columns.
+- **Row (Tuple)**: A single record in a table.
+- **Column (Attribute)**: A field that defines a property of data.
+- **Primary Key**: Uniquely identifies each record in a table.
+- **Foreign Key**: Links one table to another.

DBMS/DBMS Structured Notes/04_Normalisation.md

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+# Normalization in DBMS
+
+## What is Normalization?
+- Process of organizing data to reduce redundancy.
+- Improves efficiency and avoids anomalies.
+
+## Forms of Normalization:
+- **1NF**: No repeating groups, atomic values.
+- **2NF**: 1NF + no partial dependency.
+- **3NF**: 2NF + no transitive dependency.
+- **BCNF**: Stronger version of 3NF.

DBMS/DBMS Structured Notes/05_Acid_properties.md

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+# ACID Properties
+
+ACID ensures reliable database transactions:
+
+1. **Atomicity** → All or nothing execution.
+2. **Consistency** → Data must remain valid before and after transaction.
+3. **Isolation** → Transactions execute independently.
+4. **Durability** → Changes remain permanent even after a crash.

DBMS/DBMS Structured Notes/06_Transactions.md

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+# Transactions in DBMS
+
+- A **transaction** is a set of operations performed as a single logical unit.
+- Example: Money transfer between accounts.
+
+## Transaction Commands:
+- **COMMIT** → Save changes permanently.
+- **ROLLBACK** → Undo changes.
+- **SAVEPOINT** → Save a point to rollback partially.

DBMS/DBMS Structured Notes/07_SQL_basic_commands.md

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+## SELECT
+SELECT name, age FROM Students;
+
+## INSERT
+INSERT INTO Students (id, name, age) VALUES (1, 'Shiwans', 20);
+
+## UPDATE
+UPDATE Students SET age = 21 WHERE id = 1;
+
+## DELETE
+DELETE FROM Students WHERE id = 1;
+
+
+## USE CASES OF DBMS ##
+- **RDBMS (Relational)** → For structured data (banking, e-commerce).
+- **NoSQL DBMS** → For unstructured/large-scale data (social media, big data).
+
+
+
+
+## Popular DBMS ##
+  - MySQL
+  - PostgreSQL
+  - MongoDB
+  - SQLite

DBMS/DBMS Structured Notes/08_README.md

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+# DBMS Notes by Shiwans
+
+This folder contains beginner-friendly notes on **Database Management Systems (DBMS)**.
+
+## Index
+1. [Introduction](01_Introduction.md)
+2. [Types of DBMS](02_Types_of_DBMS.md)
+3. [Key Concepts](03_Key_Concepts.md)
+4. [Normalization](04_Normalization.md)
+5. [ACID Properties](05_ACID_Properties.md)
+6. [Transactions](06_Transactions.md)
+7. [SQL Basic Commands](07_SQL_basic_commands.md)
+8. [README](08_README.md)
+
+---
+> ✨ Contribution by **Shiwans Kumar Yadav**