Products Bought Together

Return all pairs of products that appear in the same order, with the number of orders in which they appear together. Output the pair with the smaller product_id first, ordered by count descending then product ids.

Table schema

OrderItems(order_id INT, product_id INT)

Sample data

order_id | product_id
1 | 10
1 | 20
2 | 10
2 | 20
2 | 30
3 | 20
3 | 30