Cartesian Products with CROSS JOIN in SQL

Question

Given `stores` (store_id, city) and `products` (product_id, sku), write a SQL query to generate a complete matrix of all possible store-product combinations to audit stocking gaps.

Accepted Answer

Optimal Solution:
SELECT 
  s.store_id,
  s.city,
  p.product_id,
  p.sku
FROM stores s
CROSS JOIN products p
ORDER BY s.store_id, p.product_id;

Technical Explanation:
A `CROSS JOIN` produces the Cartesian product of the two tables, generating every possible pairing between stores and products.

store_id	city	product_id	sku
1	Gurgaon	101	SKU-A
2	Bangalore	102	SKU-B

store_id	city	product_id	sku
1	Gurgaon	101	SKU-A
1	Gurgaon	102	SKU-B
2	Bangalore	101	SKU-A
2	Bangalore	102	SKU-B