MySQL count issue

Question

In my application (osCommerce) I had to modify a query that look like this:

SELECT     sql_cache distinct p.products_image, 
           p.products_subimage1, 
           pd.products_name, 
           p.products_quantity, 
           p.products_model, 
           p.products_ordered, 
           p.products_id, 
           p.products_price, 
           p.products_date_added, 
           p.products_weight, 
           p.products_length, 
           p.products_width, 
           p.products_height, 
           p.products_tax_class_id, 
           p.products_status, 
           IF(s.status, s.specials_new_products_price, NULL)             AS specials_new_products_price,
           IF(s.status, s.specials_new_products_price, p.products_price) AS final_price 
FROM       products p 
LEFT JOIN  specials s 
ON         p.products_id = s.products_id 
LEFT JOIN  products_to_categories p2c 
ON         p.products_id=p2c.products_id 
LEFT JOIN  products_description pd 
ON         p.products_id=pd.products_id 
INNER JOIN filter_association_products fap 
ON         p.products_id =fap.products_id 
LEFT JOIN  products_attributes pa 
ON         p.products_id = pa.products_id 
WHERE      p.products_status = '1' 
AND        date_sub(curdate(),INTERVAL 3000 day) <= p.products_date_added 
AND        find_in_set(fap.filter_id,'126, 130')
ORDER BY   p.products_date_added DESC, 
           pd.products_name

to end like this, for accurate results:

AND      fap.filter_id IN (126, 130)
GROUP BY p.products_id
HAVING COUNT(DISTINCT fap.filter_id) = 2;

The issue I have now is that there is the following query that is using this new query and giving me wrong results.

SELECT COUNT( DISTINCT p.products_id ) AS total
FROM products p
LEFT JOIN specials s ON p.products_id = s.products_id
LEFT JOIN products_to_categories p2c 
ON p.products_id = p2c.products_id
LEFT JOIN products_description pd 
ON p.products_id = pd.products_id
INNER JOIN filter_association_products fap ON p.products_id = fap.products_id
LEFT JOIN products_attributes pa 
ON p.products_id = pa.products_id
WHERE p.products_status =  '1'
AND DATE_SUB( CURDATE( ) , INTERVAL 3000 DAY ) <= p.products_date_added
AND fap.filter_id IN ( 126, 130 ) 
GROUP BY p.products_id
HAVING COUNT( DISTINCT fap.filter_id ) =2
ORDER BY p.products_date_added DESC , pd.products_name

Which instead of giving a result of 1 row with the count of all the product_ids in the original query, now gives a result of multiple rows (the same amount of rows as the expected total products count) with the number 1 in each of them. The main issue seems to be the GROUP BY p.products_id HAVING COUNT( DISTINCT fap.filter_id ) =2

Is there any way to modify the original query so that the count query will work correctly while still using AND fap.filter_id IN ( 126, 130 )?

Answer 1

As Gordon suggested, using a subquery should generally work. Since this query looks like a product listing query and since you are using osCommerce, you will bump into another core issue when you modify the query to use a subquery: The count query of the split page results will fail as it does not support subqueries. To resolve this also, you will need to modify the core code in catalog/includes/classes/split_page_results.php

Change:

$count_query = tep_db_query("select count(" . $count_string . ") as total " . substr($this->sql_query, $pos_from, ($pos_to - $pos_from)));

To:

$count_query = tep_db_query("select count(*) as total from (" . $this->sql_query . ") AS derivedtable1");

More details here: http://forums.oscommerce.com/topic/290110-class-splitpageresults/