How to JOIN Three Tables in SQL

SELECT o.order_id, c.name AS customer, p.name AS product, o.quantity
FROM orders o
INNER JOIN customers c ON o.customer_id = c.id
INNER JOIN products p ON o.product_id = p.id
WHERE o.created_at >= '2026-01-01'
ORDER BY o.created_at DESC;

This query pulls from three tables — orders, customers, and products — joining them on their foreign key relationships to build a complete picture of each order.

1. FROM orders o — start with the orders table (aliased as 'o')
2. INNER JOIN customers c ON o.customer_id = c.id — add customer names
3. INNER JOIN products p ON o.product_id = p.id — add product names
4. WHERE filters to orders from 2026 onward
5. ORDER BY sorts newest orders first

• INNER JOIN excludes orders with no matching customer or product
• Use LEFT JOIN to include orders even without a matching record
• Missing indexes on join columns can make this query very slow
• NULL values in join columns are never matched by JOIN