Average Review RatingsCompany: Shopify | Difficulty: easy

Calculate the average review rating for each product.

Return the columns in this exact order: product_id and avg_rating. Round the average rating to two decimal places and sort the results by product_id in descending order.

Reviews with NULL ratings should be ignored when calculating the average.

Table Schema

Table	Column	Type
`product_reviews`	`review_id`	integer
`product_reviews`	`product_id`	integer
`product_reviews`	`rating`	decimal(2,1)

Example Input: `product_reviews`

review_id	product_id	rating
1	5001	5.0
2	5001	4.0
3	5002	3.0
4	5002	NULL

Example Output Explanation

Product 5001 has an average rating of 4.50 from ratings of 5.0 and 4.0. Product 5002 has one valid rating of 3.0 (returned as 3.00); its NULL rating is ignored. The output is sorted by product_id in descending order, meaning 5002 will appear before 5001.

SchemaDROP TABLE IF EXISTS product_reviews; CREATE TABLE product_reviews ( review_id INT, product_id INT, rating DECIMAL(2,1) ); INSERT INTO product_reviews VALUES (1, 5001, 5.0), (2, 5001, 4.0), (3, 5002, 3.0), (4, 5002, NULL);← All SQL Challenges · Shopify Questions · Learn SQL Free