MySQL Having + OrderBy returning fewer rows than expected

I have the following query:

select 
    products.id,
    products.description,
    products.barcode,
    getStock(products.id, 'Production') AS total_stock   
from `products`
having total_stock > 0
order by products.description asc

Which is pretty straight forward. However, the results returned are incorrect. It’s currently returning 2 rows and if I remove the order by clause it returns 4000 rows.

select 
    products.id,
    products.description,
    products.barcode,
    getStock(products.id, 'Production') AS total_stock   
from `products`
having total_stock > 0 

Applying a group by clause, like referred in enumerous topics such as Error with ORDER BY used with HAVING Clause, has no success, as the number of rows returned is, again, 2.

select 
    products.id,
    products.description,
    products.barcode,
    getStock(products.id, 'Production') AS total_stock   
from `products`
group by products.id, products.description, products.barcode 
having total_stock > 0 
order by products.description asc

What am I missing?

Edit 1: The getStock function

DELIMITER $$
CREATE FUNCTION getStock (productId INT, environment VARCHAR(255)) RETURNS INT(11)
BEGIN                 
    DECLARE qty INT(11) DEFAULT 0;
    
    SELECT SUM(pw.stock) INTO qty
        FROM products_wholesalers AS pw
        INNER JOIN subscriptions AS subscription ON subscription.id = pw.subscription_id
        WHERE pw.product_id = productId 
            AND pw.active = true
            AND subscription.type = 'Wholesaler'
            AND subscription.active = true
            AND subscription.environment = environment;
    
    RETURN qty;
END $$

>Solution :

The issue is related to how SQL are processed, with ‘HAVING’ and ‘ORDER BY’ combination. Your query return 4000 rows because it’s not sorting the results by description so it returns all rows meet HAVING condition.

In SQL, HAVING clause filters results after grouping done by the GROUP BY clause and ORDER BY clause sorts rows in the result set befure it’s returned.

To solve, you can try to use a subquery

SELECT * FROM (
    SELECT 
        products.id,
        products.description,
        products.barcode,
        getStock(products.id, 'Production') AS total_stock   
    FROM `products`
) AS subquery
WHERE total_stock > 0
ORDER BY description ASC;