Cross Join

A CROSS JOIN returns the Cartesian product of two tables - every row from the first table combined with every row from the second, with no matching condition required.

Basic Syntax

SELECT c.first_name, p.product_name
FROM customers c
CROSS JOIN products p;

If customers has 10 rows and products has 5 rows, this returns 10 x 5 = 50 rows - every possible customer-product pairing.

When to Use a Cross Join

• Generating all possible combinations, such as pairing every size with every color for a product catalog
• Building a complete date x category grid before filling in actual data
• Creating test data with every possible combination of input values