Introduction to SQL + Creating Your First Database & Tables

What You Will Learn in This Lesson

In this lesson, we will cover:

What SQL is and why it’s important
How databases, tables, rows, and columns work
How to install / access a SQL environment
How to create your first database
How to create tables we will use throughout this entire SQL course
How to insert sample data
How to run your first SELECT queries

This lesson builds the foundation for everything we will learn later.

What is SQL?

SQL (Structured Query Language) is a standard language used to store, retrieve, update, and manage data inside a database.

Whenever you:

build analytics
design dashboards
write ETL pipelines
work with data warehouses
do backend development

…you use SQL.

SQL is used in:

MySQL
PostgreSQL
SQL Server
Oracle
Snowflake
BigQuery
Databricks SQL

Even though each database has small differences, the core SQL syntax is the same.

What is a Database?

A database is a structured container where we store data.

Inside a database, we have:

Component	Meaning
Table	A structured data grid (rows + columns)
Row	A single record (e.g., one customer)
Column	A data field (e.g., name, email)
Primary Key	A unique identifier
Foreign Key	Link between related tables

Setting Up Your SQL Environment

You can run SQL on:

Option 1 — Local MySQL

Download from: https://dev.mysql.com/downloads/

Option 2 — Online SQL Editors

Option 3 — VS Code with SQLite Extension

For this tutorial series, we use MySQL syntax, but everything works on PostgreSQL and SQL Server too.

Create Your Database

Let’s start by creating a database called:datatorials_dbCopy

Run:

Now switch to the database:CREATE DATABASE datatorials_db; CopyUSE datatorials_db; Copy

Tables We Will Use Throughout This Course

We will create 4 core tables that represent a small sales system:

1. customers

Stores customer information.

2. products

List of products.

3. orders

High-level order information.

4. order_items

Each item inside an order.

This structure lets us practice:

SELECT
JOIN
GROUP BY
Window functions
Subqueries
CTEs
Aggregations
DML
DDL
Real-world reporting

Step 1 — Create the `customers` Table

CREATE TABLE customers ( customer_id INT PRIMARY KEY AUTO_INCREMENT, full_name VARCHAR(100), email VARCHAR(120), city VARCHAR(50), country VARCHAR(50), signup_date DATE ); Copy

Step 2 — Create the `products` Table

CREATE TABLE products ( product_id INT PRIMARY KEY AUTO_INCREMENT, product_name VARCHAR(100), category VARCHAR(50), price DECIMAL(10,2) ); Copy

Step 3 — Create the `orders` Table

CREATE TABLE orders ( order_id INT PRIMARY KEY AUTO_INCREMENT, customer_id INT, order_date DATE, total_amount DECIMAL(12,2), FOREIGN KEY (customer_id) REFERENCES customers(customer_id) ); Copy

Step 4 — Create the `order_items` Table

CREATE TABLE order_items ( item_id INT PRIMARY KEY AUTO_INCREMENT, order_id INT, product_id INT, quantity INT, price_per_unit DECIMAL(10,2), FOREIGN KEY (order_id) REFERENCES orders(order_id), FOREIGN KEY (product_id) REFERENCES products(product_id) ); Copy

Insert Sample Data

Customers:

INSERT INTO customers (full_name, email, city, country, signup_date) VALUES ('Ali Raza', 'ali@example.com', 'Lahore', 'Pakistan', '2023-01-12'), ('Sara Khan', 'sara@example.com', 'Karachi', 'Pakistan', '2023-03-22'), ('John Doe', 'john@example.com', 'New York', 'USA', '2023-02-10'); Copy

Products:

INSERT INTO products (product_name, category, price) VALUES ('Laptop', 'Electronics', 1200.00), ('Keyboard', 'Electronics', 45.00), ('Mobile Phone', 'Electronics', 900.00), ('Office Chair', 'Furniture', 150.00); Copy

Orders:

INSERT INTO orders (customer_id, order_date, total_amount) VALUES (1, '2023-05-12', 1245.00), (2, '2023-05-15', 900.00), (3, '2023-05-20', 150.00); Copy

Order Items:

INSERT INTO order_items (order_id, product_id, quantity, price_per_unit) VALUES (1, 1, 1, 1200.00), (1, 2, 1, 45.00), (2, 3, 1, 900.00), (3, 4, 1, 150.00); Copy

Run Your First Query

Try:SELECT * FROM customers; CopySELECT full_name, city, country FROM customers; Copy

Try Your First JOIN

To see orders with customer names:SELECT orders.order_id, customers.full_name, orders.order_date, orders.total_amount FROM orders JOIN customers ON orders.customer_id = customers.customer_id; Copy