Learn SQL Introduction: What Even Is SQL?

I still remember the first time I ran an SQL query. It was on an old customer orders database during a college lab. I typed something like:

SELECT * FROM orders;

And… nothing happened. Or at least, I thought nothing happened. Turns out, it did work I just didn’t know what to look for.

That’s the kind of journey SQL takes you on.

If you’re new to SQL (Structured Query Language), welcome you’re in exactly the right place. Whether you’re hoping to become a data analyst, backend developer, database admin, or just someone who wants to make sense of messy data, this guide will help you get started in a practical, no-fluff way.

What You’ll Learn

• What SQL is and where it’s used
• How to write your first working queries
• Real-world examples of using SQL
• Key SQL commands: SELECT, INSERT, UPDATE, DELETE
• Understanding tables, rows, columns, and keys
• Bonus tips on learning without overwhelm

Let’s dive in and actually see what SQL is about, not just read about it.

What is SQL? And Why Should You Care?

Think of SQL as the universal language for talking to databases.

Whether you’re analyzing user activity, building an e-commerce backend, or writing reports for business teams. SQL helps you ask databases questions like:

• “How many users signed up last week?”
• “What were the top 10 selling products in June?”
• “Give me all orders where the price is over $500.”

And unlike many programming languages, SQL is declarative you don’t tell the database how to find the answer. You tell it what you want, and it figures out how to get it.

Where is SQL Used?

SQL is everywhere:

Even if your main work is in Python or JavaScript, chances are you’ll still need to write SQL.

Your First Look at a Database

A database is just a structured way to store data. Inside a database, data lives in tables just like Excel sheets.

Let’s take a simple users table:

And here’s your first real SQL query:

SELECT name, email FROM users;

This tells the database:

“Give me the name and email of every user in the table.”

That’s it.

You’ve officially written a valid SQL statement.

The Most Important SQL Commands You Must Know

Let’s break down the top commands used in nearly every SQL job with relatable use cases.

1. SELECT – Fetch Data

SELECT * FROM users;

Selects all columns from the users table. * is a wildcard meaning “everything.”

With filters:

SELECT name FROM users WHERE signup_date >= '2025-06-01';

Gets users who signed up on or after June 1st.

2. INSERT – Add Data

INSERT INTO users (name, email, signup_date)
VALUES ('Fatima Sheikh', 'fatima@example.com', '2025-06-16');

Adds a new row to the table.

3. UPDATE – Modify Existing Data

UPDATE users
SET email = 'newemail@example.com'
WHERE id = 2;

Updates Samir’s email address.

4. DELETE – Remove Data

DELETE FROM users WHERE id = 1;

Removes Ayesha from the table.

Be careful DELETE is permanent unless your database supports rollback.

Real-World Example: Filtering Customers by Purchase History

Let’s say you have a customers table and a purchases table.

-- Customers table
id | name
1  | Sara
2  | Imran

-- Purchases table
id | customer_id | item        | price
1  | 1           | Headphones  | 120
2  | 2           | Keyboard    | 80
3  | 1           | Smartphone  | 600

Goal: Find customers who bought something over ₹100

SELECT DISTINCT c.name
FROM customers c
JOIN purchases p ON c.id = p.customer_id
WHERE p.price > 100;

You’re now writing JOINs a powerful way to combine data across tables.

SQL Keywords Cheat Sheet

You’ll use these over and over.

How SQL Works Behind the Scenes

When you run an SQL query, the database:

1. Parses the query for syntax errors
2. Plans the execution (which indexes to use, which order to scan tables)
3. Executes it
4. Returns results

You don’t need to know this in depth, but understanding this helps you optimize queries later (especially for large datasets).

Common Beginner Pitfalls (And How to Avoid Them)

How to Practice SQL Like a Pro (For Free)

You don’t need a paid course to get good at SQL.

Try These Free Resources:

• SQLBolt
• Mode SQL Tutorial
• LeetCode SQL Challenges

Or install SQLite locally and play around with a dummy dataset.

Final Thoughts: Why SQL Will Never Die

SQL has been around since the 1970s and it’s still essential in 2025.

Why? Because the world runs on data. And SQL is how we interact with it.

Whether you’re debugging an app, extracting data for a dashboard, or just analyzing trends in Excel exports knowing SQL gives you superpowers.

So don’t wait for some course or bootcamp.

Open a SQL playground, write a query, and start exploring.

Trust me: It’s way more fun when you stop reading and start doing.

If you’re just getting started with Python or planning to use SQL for analysis, check out:

• Exploratory Data Analysis in Python – Full Guide
• Data Cleaning in Python – Handle Missing, Messy, Wrong Data

Additional Resources:

Want a full visual guide to SQL basics? Start here:
W3Schools SQL Tutorial

Frequently Asked Questions