Joining Tables with INNER JOIN

INNER JOIN is one of the most powerful SQL concepts. It combines rows from two tables where they have matching values.

Why Do We Need JOINs?

Real databases split data into multiple tables to avoid repetition. For example:

• customers table: customer info (name, email)
• orders table: order info (date, status, customer_id)

To see "which customer placed which order", we need to JOIN them.

Syntax

SELECT columns
FROM table1
INNER JOIN table2 ON table1.column = table2.column;

How It Works

SELECT orders.id, customers.name
FROM orders
INNER JOIN customers ON orders.customer_id = customers.id;

For each order, SQL finds the customer whose id matches the order's customer_id.

Visualization

orders.id	orders.customer_id	→	customers.id	customers.name
1	101	→	101	Alice
2	102	→	102	Bob

⚠️ INNER JOIN Only Returns Matches

If a customer has no orders, they won't appear. If an order has no matching customer, it won't appear either.

Our Tables

• orders: id, customer_id, order_date, status
• customers: id, name, email

Your Task

Join orders with customers to show:

• Order ID
• Customer name
• Order status