MySQL的計數問題

Question

在我的應用程序（自從）我不得不修改的查詢看起來像這樣：

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 

就這樣結束，對於準確的結果：

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

我有問題現在是有以下查詢使用這個新的查詢，並給我錯誤的結果。

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 

而不是給1行的所有product_id S IN原始查詢的計數的結果是，現在給多行的結果（相同數量的行爲預期的總產品數）與它們中的每一個都是數字1。 主要問題似乎是GROUP BY p.products_id HAVING COUNT(DISTINCT fap.filter_id) =2

是否有任何方法來修改原始查詢，以便在仍使用AND fap.filter_id IN (126, 130)時計數查詢將正常工作？

Answer 1

正如戈登建議的那樣，使用子查詢通常應該可以工作。 由於此查詢看起來像產品列表查詢，並且因爲您使用的是osCommerce，所以當您修改查詢以使用子查詢時，您會遇到另一個核心問題： 拆分頁面結果的計數查詢將失敗，因爲它不支持子查詢。 要還解決這個問題，你需要修改核心代碼catalog/includes/classes/split_page_results.php

變化：

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

要：

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

更多細節在這裏：http://forums.oscommerce.com/topic/290110-class-splitpageresults/

Answer 2

您需要使用子查詢來獲得您想要的結果：

select count(*) 
from (<old query here>) s; 

您需要在產品ID級別聚合得到滿足初始條件的產品。計算這些產品的數量需要另一個聚合。