SQL Query to find Woocommerce products that have not sold

Question

I am trying to set up a query that will find products that havn't sold within a time frame and a count. For example I want to find all products within the last year that have sold less than 50 times. I am not sure what is wrong with my query but here it is:

SELECT * FROM `wp_posts` t1 
  INNER JOIN `wp_woocommerce_downloadable_product_permissions` t2 
    ON t1.ID = t2.product_id 
  WHERE t2.access_granted >= "2016-04-30 00:00:00" 
  HAVING COUNT(t2.product_id) <= 50;

The result is always empty even though I know that there are products that have sold less than 50 times within the last year.

Answer 1

Result is empty because you are using Having clause without group by which will count all the rows in the table.
I am assuming your table contains more than 50 rows hence the result will always be empty as count(t2.product_id) will always be > 50.

Try this:

SELECT t2.product_id
FROM `wp_posts` t1 INNER JOIN `wp_woocommerce_downloadable_product_permissions` t2 ON t1.ID = t2.product_id 
WHERE t2.access_granted >= "2016-04-30 00:00:00" 
group by t2.product_id
HAVING COUNT(t2.product_id) <= 50;