Types of Databases

Types of Database-tutorial

Video Tutorial Discussion

Now that you know how a database is structured with tables, rows, and columns

let us explore the two major types of databases you will encounter in the real world:

Relational Databases (SQL-based)

Non-Relational Databases (NoSQL-based)

Both store data but in different ways and for different needs.

1. Relational Databases (SQL Databases)

Relational databases organize data into tables (rows and columns).

Each table stores specific information and tables are connected through relationships.

Think of it like a well-structured Excel sheet each sheet (table) has its own data, and you can link them using a common column.

Key Concepts

Term	Meaning
Table	Collection of data (like a spreadsheet)
Row (Record)	Single entry of data
Column (Field)	Attribute or property of data
Primary Key	Unique ID for each record
Foreign Key	A link between two tables

Example: Online Store Database

Let us say you own an e-commerce store, You have two tables Customers and Orders.

Table: Customers

CustomerID	Name	City
1	Amit Kumar	Delhi
2	Rohit Das	Mumbai

Table: Orders

OrderID	CustomerID	Product	Price
101	1	Laptop	50,000
102	2	Headphones	2,000

Here,

The Customers table stores all customer details.

The Orders table stores order information.

The CustomerID column in both tables helps us connect which customer placed which order even if we don’t know the exact SQL command yet.

Later, when you learn SQL queries, you’ll see how we can combine this data to show results together.

Foreign Key

You can simply say:

Here, the customerID in the Orders table refers to the Customer in the Customers table.
This connection between tables is called a relationship, and you will learn more about it when we study Foreign Keys later.

Example

SELECT Customers.Name, Orders.Product, Orders.Price
FROM Customers
JOIN Orders
ON Customers.CustomerID = Orders.CustomerID;

Output

Name	Product	Price
Amit Kumar	Laptop	50,000
Rohit Das	Headphones	2,000

Examples of Relational Databases

MySQL

PostgreSQL

Oracle Database

Microsoft SQL Server

2. Non-Relational Databases (NoSQL Databases)

Not all data fits perfectly into tables.

Sometimes we have unstructured or semi-structured data like images, comments, or user preferences.

That is where Non-relational (NoSQL) databases come in.

They store data in flexible forms such as:

Documents (JSON, XML)

Key-Value pairs

Graphs

Wide Columns

There are no fixed schemas each record can look different.

Real Life Analogy

Imagine a digital diary where every page (document) may have different details.
Unlike a relational table, there is no strict rule that every page must have the same columns.

Example: Storing Customer Data in MongoDB (Document Format)

{
  "CustomerID": 1,
  "Name": "Amit Kumar",
  "City": "Delhi",
  "Orders": [
    { "Product": "Laptop", "Price": 50000 },
    { "Product": "Mouse", "Price": 1200 }
  ]
}

Here:

Everything about Amit her details and orders is stored together in one document.

This makes retrieval fast and flexible.

Examples of Non-Relational Databases

MongoDB (Document-based)

Redis (Key-Value store)

Cassandra (Wide Column)

Neo4j (Graph-based)

Firebase (Cloud-based)

Difference Between SQL and NoSQL

Feature	Relational (SQL)	Non-Relational (NoSQL)
Structure	Tables (rows & columns)	Documents, key-value, graphs
Schema	Fixed	Flexible
Language	SQL	JSON / APIs
Best For	Structured data, transactions	Unstructured or big data
Examples	MySQL, PostgreSQL	MongoDB, Firebas

Two Minute Drill

Databases are of two main types : Relational (SQL) and Non-Relational (NoSQL).

Relational = Tables + Keys + Relationships.

Non-relational = Documents + Flexibility + Scalability.

NoSQL uses nested documents or references.

Both are essential in modern development often used together.