用組數來計算，返回行數

Question

我正在嘗試做一個需要group by的count查詢。但是當我得到我的結果時，我得到了正確數量的行，但他們的總數列中的計數，而不是我想要的行數量。

SELECT Count(p.products_id) AS total 
FROM products p 
     LEFT JOIN specials s 
       ON p.products_id = s.products_id 
     LEFT JOIN manufacturers m 
       ON p.manufacturers_id = m.manufacturers_id 
     JOIN products_description pd 
     ON p.products_id = pd.products_id 
     JOIN products_to_categories p2c 
     ON p.products_id = p2c.products_id 
     INNER JOIN products_specifications ps7 
       ON p.products_id = ps7.products_id 
     LEFT JOIN products_to_icon p2i 
       ON p.products_id = p2i.products_id 
     LEFT JOIN products_icons pi 
       ON p2i.icons_id = pi.icons_id 
WHERE p.products_status = '1' 
     AND pd.language_id = '1' 
     AND ps7.specification IN ('Polycotton') 
     AND ps7.specifications_id = '7' 
     AND ps7.language_id = '1' 
GROUP BY p.products_id 

我能做些什麼來使它給我總行數，而不是將每個產品ID的總數分組爲總數。

什麼樣我得到的：

total 
1 
2 
1 
1 
2 
2 

我想要什麼：

total 
6 

Answer 1

選項1：

Count(t.products_id) AS total FROM (
    SELECT p.products_id 
    FROM products p 
      LEFT JOIN specials s 
        ON p.products_id = s.products_id 
      LEFT JOIN manufacturers m 
        ON p.manufacturers_id = m.manufacturers_id 
      JOIN products_description pd 
      ON p.products_id = pd.products_id 
      JOIN products_to_categories p2c 
      ON p.products_id = p2c.products_id 
      INNER JOIN products_specifications ps7 
        ON p.products_id = ps7.products_id 
      LEFT JOIN products_to_icon p2i 
        ON p.products_id = p2i.products_id 
      LEFT JOIN products_icons pi 
        ON p2i.icons_id = pi.icons_id 
    WHERE p.products_status = '1' 
      AND pd.language_id = '1' 
      AND ps7.specification IN ('Polycotton') 
      AND ps7.specifications_id = '7' 
      AND ps7.language_id = '1' 
    GROUP BY p.products_id 
)t 

這將包括行，首先將返回一個0 ...

如果你不希望出現這種情況，然後添加下GROUP BY線這條線：

HAVING count(p.products_id) > 0 

選項2： 只需使用php函數mysql_num_rows(),mysqli_num_rows()或PDO等效項，具體取決於您使用的是哪一組mysql函數。 （不建議使用此選項，因爲它對於服務器而言是不必要的開銷。）

Answer 2

巢一切都在一個子查詢：

SELECT COUNT(*) FROM (
     [your query here] 
) AS subquery 

Answer 3

Use ROLLUP

GROUP BY p.products_id WITH ROLLUP; 

編輯：我假設你正在使用MySQL。其他DBMS有不同的語法：

GROUP BY p.products_id, rollup(p.SOME_COLUMN);