Introduction to SQL

Introduction to SQL-tutorial

In today’s digital era, everything you do online whether it is logging into a website, watching a video, or shopping for your favorite product generates data.
But have you ever wondered how websites remember your login, how shopping apps store your cart items, or how YouTube recommends videos that match your interests?

The secret behind all this is a database a system designed to store and organize information and the language that helps manage these databases is SQL (Structured Query Language).

What is SQL ?

SQL (Structured Query Language) is a standard programming language used to communicate with and manage data stored in relational databases.

You can think of a database as a digital warehouse that stores information in tables rows and columns much like an Excel sheet.

SQL helps you:

Create new databases and tables

Insert or update data

Query and analyze information

Delete data when it’s no longer needed

It is the universal language of data management.

SQL is how you “talk” to databases to get, store, or manage information efficiently.

Why Learn SQL ?

Whether you are a developer, analyst, or student SQL is a must-have skill in today’s data-driven world.

Here is why:

1. Universal and In-Demand

SQL works with most popular databases like MySQL, PostgreSQL, Oracle, SQL Server, and SQLite.

It is used by almost every tech company from startups to giants like Google and Amazon.

2. Easy to Learn

SQL is simple, readable, and close to English.

You can start writing useful commands on day one!

3. Versatile Career Applications

Whether you want to become a:

Backend Developer

Data Analyst

Data Engineer

BI (Business Intelligence) Developer

SQL is your foundation.

4. Works Behind Every Application

Every login, every transaction, every “Search” button click somewhere, an SQL query runs in the background fetching or updating data.

5. Essential for Data Analytics

Before Python or Excel analyzes the data SQL fetches it. It is your first step into data science and analytics.

Example

Imagine you run an online bookstore called QuipoBooks.

Every book you sell along with details like author, price, and available stock is stored in a database table called Books. Think of this table as a neatly organized digital inventory sheet.

Here is how your table looks:

Book ID	Title	Author	Price	Quantity
1	Atomic Habits	James Clear	550	10
2	Deep Work	Cal Newport	499	5
3	The Alchemist	Paul Coelho	399	8

Now, suppose a customer asks:

"Show me all books that cost more than ₹400."

Without SQL, you have to manually scan your inventory very time-consuming!

But with SQL, it is just one simple query:

SELECT Title, Author, Price
FROM Books
WHERE Price > 400;

What is happening here?

SELECT - tells the database which columns you want to see (Title, Author, Price).

FROM - specifies the table (Books) to fetch data from.

WHERE - filters rows that meet your condition (Price > 400).

Output

Title Author Price
Atomic Habits James Clear 550
Deep Work Cal Newport 499

Title	Author	Price
Atomic Habits	James Clear	550
Deep Work	Cal Newport	499

In a matter of seconds, SQL gives you exactly what you need accurate, filtered, and ready to use.

SQL in the Real World

Here is where you will find SQL in action:

Websites storing user accounts (Facebook, Instagram, Amazon)

Banking systems tracking transactions

E-commerce platforms managing products and orders

Mobile apps storing login data and user preferences

Analytics dashboards fetching real-time insights

SQL is everywhere from your favorite apps to billion-dollar enterprise systems.

Key Point

SQL = Structured Query Language

Used to store, retrieve, update, and delete data in databases

Works with tables (rows = records, columns = fields)

Performs CRUD operations Create, Read, Update, Delete

Easy to learn, powerful to use, and essential for every tech career