SQL Tutorial for Beginners – Learn SQL with Examples (2025)

Introduction to SQL

What is SQL?

SQL stands for Structured Query Language. It’s the universal language for interacting with relational databases.
You can use SQL to:

• Retrieve data
• Insert records
• Update entries
• Delete data

From small projects to enterprise-grade apps — SQL powers them all!

Why is SQL Important?

Because data runs the world!
Whether it’s your:

• Amazon orders
• Netflix recommendations
• Company analytics

All of it lives in databases — and SQL helps you manage it.

Getting Started with SQL

Basic SQL Syntax

SELECT * FROM customers;

SQL keywords are usually in uppercase
Each statement ends with a ;

Set Up Your SQL Environment

Choose from:

MySQL
PostgreSQL
SQLite
SQL Server

Practice for free:

• SQLFiddle
• DB Fiddle
• W3Schools SQL Editor

SQL Data Types

Numeric

• INT, FLOAT, DECIMAL

String

• CHAR, VARCHAR, TEXT

Date & Time

• DATE, TIME, DATETIME, TIMESTAMP

Full List of MySQL Data Types

SQL Commands Overview

DDL (Data Definition Language)

• CREATE, ALTER, DROP

DML (Data Manipulation Language)

• INSERT, SELECT, UPDATE, DELETE

DCL (Data Control Language)

• GRANT, REVOKE

TCL (Transaction Control Language)

• COMMIT, ROLLBACK, SAVEPOINT

Creating and Modifying Tables

CREATE

CREATE TABLE users (
    id INT PRIMARY KEY,
    name VARCHAR(50),
    email VARCHAR(100)
);

ALTER

ALTER TABLE users ADD COLUMN age INT;

DROP

DROP TABLE users;

CRUD Operations in SQL

INSERT

INSERT INTO users (id, name, email)
VALUES (1, 'John Doe', 'john@example.com');

SELECT

SELECT * FROM users;

UPDATE

UPDATE users
SET name = 'Jane Doe'
WHERE id = 1;

DELETE

DELETE FROM users WHERE id = 1;

Filtering & Sorting Data

WHERE

SELECT * FROM users WHERE age > 30;

ORDER BY

SELECT * FROM users ORDER BY name ASC;

🎚️ LIMIT

SELECT * FROM users LIMIT 5;

SQL Functions & Operators

Aggregate

• SUM(), AVG(), COUNT(), MIN(), MAX()

String

• CONCAT(), SUBSTRING(), LENGTH()

Logical

• AND, OR, NOT

W3Schools SQL Functions

SQL Joins

INNER JOIN

SELECT users.name, orders.amount
FROM users
INNER JOIN orders ON users.id = orders.user_id;

LEFT JOIN

SELECT users.name, orders.amount
FROM users
LEFT JOIN orders ON users.id = orders.user_id;

RIGHT JOIN

(Supported in some DBMS)

FULL OUTER JOIN

(Combine LEFT + RIGHT for MySQL alternative)

Grouping Data

GROUP BY

SELECT age, COUNT(*) FROM users GROUP BY age;

HAVING

SELECT age, COUNT(*) FROM users GROUP BY age HAVING COUNT(*) > 1;

SQL Subqueries

SELECT name FROM users
WHERE id IN (
  SELECT user_id FROM orders WHERE amount > 100
);

• Correlated – Depends on outer query
• Non-correlated – Independent query

Indexes and Views

Create Index

CREATE INDEX idx_name ON users(name);

👁️ Create View

CREATE VIEW user_emails AS
SELECT name, email FROM users;

SQL Constraints

Basic Constraints

CREATE TABLE products (
    id INT PRIMARY KEY,
    name VARCHAR(100) NOT NULL UNIQUE
);

Advanced Constraints

CREATE TABLE orders (
    id INT,
    user_id INT,
    FOREIGN KEY (user_id) REFERENCES users(id),
    amount DECIMAL CHECK (amount > 0),
    status VARCHAR(10) DEFAULT 'Pending'
);

SQL Best Practices

🟩 Use meaningful table/column names
🟩 Stick to snake_case
🟩 Avoid SELECT *
🟩 Normalize data for efficiency
🟩 Create indexes for search-heavy fields

Summary

SQL is a foundational skill for:

• Data analysts
• Backend developers
• BI professionals

With practice and projects, you’ll master querying, filtering, and managing data like a pro.

Pro Tip: Use SQL in combination with Python or Excel for next-level data analysis.

FAQs

Q1: What’s the difference between SQL and MySQL?
SQL is a language, while MySQL is a database system using SQL.

Q2: Is SQL enough for a data job?
It’s a great start! Combine it with Python or BI tools.

Q3: How long to learn SQL?
Basics can be learned in 2–3 weeks with regular practice.

Q4: Can I use SQL without coding experience?
Absolutely! It’s one of the easiest programming languages to start with.

Q5: Where can I practice SQL online?
W3Schools, LeetCode, SQLZoo, HackerRank