LEFT JOIN

LEFT JOIN includes ALL rows from the left table, even if there's no match in the right table. Unmatched rows get NULL values.

INNER JOIN vs LEFT JOIN

Type	What it returns
<code>INNER JOIN</code>	Only rows that match in BOTH tables
<code>LEFT JOIN</code>	ALL rows from the left table + matches from right

Visualization

INNER JOIN (customers → orders):

Customer	Order
Alice	Order 1
Bob	Order 2
~~Carol~~	~~(no orders — excluded!)~~

LEFT JOIN (customers → orders):

Customer	Order
Alice	Order 1
Bob	Order 2
Carol ✅	NULL (no orders — still included!)

Syntax

SELECT c.name, o.id
FROM customers c
LEFT JOIN orders o ON c.id = o.customer_id;

The left table (customers, written after FROM) keeps all its rows.

💡 When to Use LEFT JOIN

• Find customers who have never ordered
• See all products, even those never sold
• Any time you need to include rows without matches

Your Task

Find all customers and their orders (including customers with no orders).