3521. Find Product Recommendation Pairs

Table: ProductPurchases +-------------+------+ | Column Name | Type | +-------------+------+ | user_id | int | | product_id | int | | quantity | int | +-------------+------+ (user_id, product_id) is the unique key for this table. Each row represents a purchase of a product by a user in a specific quantity. Table: ProductInfo +-------------+---------+ | Column Name | Type | +-------------+------