Sort products by number of reviews

I have a mysql database with

• table '开发者_StackOverflowproduct' containing columns 'product_id', 'name', 'price'
• table 'review' containing columns 'review_id', 'product_id', 'review_content'

I want to retrieve results for 'product_id' = 123, but sort if by number of reviews. I am able to find the number of reviews for a particular product using COUNT('review_id'), but how do I sort the results by number of reviews?

Since you're presumably selecting COUNT('review_id') in your query, you can simply add ORDER BY COUNT('review_id') DESC at the end.

Try this to get all the products and the number of reviews on each:

SELECT P.*, IFNULL(COUNT(R.product_ID),0) AS NumReviews
FROM Product AS P
LEFT JOIN Review AS R ON R.product_id = p.product_id
ORDER BY  COUNT(R.product_ID) DESC

To save doing the count twice use: count('review_id') as num_reviews and then order by num_reviews

If you want the products with the most reviews first...

SELECT P.product_id, 
       IFNULL(COUNT(R.product_ID),0) as "Reviews"
FROM product as P
LEFT JOIN review as R ON P.product_ID = R.product_id
GROUP BY P.product_id
ORDER BY Review DESC;

...otherwise switch DESC with ASC.