如何獲得列值不等於零的平均值？

Question

我有一個查詢

Select AVG(((cast(c.rating1 as Float)+ cast(c.rating2 as Float)+cast (c.rating3 as Float)+cast(c.rating4 as Float)+cast(c.rating5 as Float))/5)) 
From CSEReduxResponses c 
Where 
    c.execoffice_date BETWEEN DATEADD(MONTH, DATEDIFF(MONTH, 0, @today)-1, 0) 
AND DATEADD(MONTH, DATEDIFF(MONTH, -1, @today)-1, -1) 
AND c.execoffice_status =1 
AND C.rating1 <> 0 AND C.rating2 <> 0 AND C.rating3 <> 0 AND C.rating4 <> 0 AND 
C.rating5 <> 0 

當我得到等級1-5的平均水平，但我還指望收視率，其中等於「0」。

我怎樣才能得到它只能算一個等級，其中等級[X]不等於「0」？ 它仍然會計數，除了除以5之外，它會將它除以有多少列不是'0'。

我創建了一個< http://sqlfiddle.com/#!3/570fa/7>

Answer 1

嘗試使用VALUES獲得非0值的每一行的平均水平。

SELECT 
(
    SELECT AVG(rating) 
    FROM (VALUES 
     (cast(c.rating1 as Float)), 
     (cast(c.rating2 as Float)), 
     (cast(c.rating3 as Float)), 
     (cast(c.rating4 as Float)), 
     (cast(c.rating5 as Float)) 
    ) AS v(rating) 
    WHERE v.rating <> 0 
) avg_rating 
From CSEReduxResponses c 
Where 
    c.execoffice_date BETWEEN DATEADD(MONTH, DATEDIFF(MONTH, 0, @today)-1, 0) 
AND DATEADD(MONTH, DATEDIFF(MONTH, -1, @today)-1, -1) 
AND c.execoffice_status = 1 

http://sqlfiddle.com/#!3/570fa/26

我從刪除以下條件的WHERE

AND C.rating1 <> 0 AND C.rating2 <> 0 AND C.rating3 <> 0 AND C.rating4 <> 0 AND 
C.rating5 <> 0 

因爲如果你把它留在，你只計算有5個非0評分行平均水平，我猜猜這不是你的意圖。

要在所有行非0評分的總數除以所有非0評分的總和得到非0評分的平均值。

SELECT 
    CAST(SUM(sum_rating) as float)/SUM(count_rating) 
From CSEReduxResponses c 
CROSS APPLY (
    SELECT SUM(rating), COUNT(rating) 
    FROM (VALUES 
     (c.rating1), 
     (c.rating2), 
     (c.rating3), 
     (c.rating4), 
     (c.rating5) 
    ) AS v(rating) 
    WHERE v.rating <> 0 
) AS x (sum_rating, count_rating) 
Where 
    c.execoffice_date BETWEEN DATEADD(MONTH, DATEDIFF(MONTH, 0, GETDATE())-1, 0) 
AND DATEADD(MONTH, DATEDIFF(MONTH, -1, GETDATE())-1, -1) 
AND c.execoffice_status = 1 

http://sqlfiddle.com/#!3/570fa/35

正如其他人所說，你應該考慮如果可能的話你的正常化表。

Answer 2

這是不漂亮但應該工作：

SELECT AVG((... SUM of 5 ratings ...)/
      (CASE WHEN rating1 > 0 THEN 1 ELSE 0 END + 
      CASE WHEN rating2 > 0 THEN 1 ELSE 0 END + 
      CASE WHEN rating3 > 0 THEN 1 ELSE 0 END + 
      CASE WHEN rating4 > 0 THEN 1 ELSE 0 END + 
      CASE WHEN rating5 > 0 THEN 1 ELSE 0 END)) 
    FROM ... 
    WHERE ... 

做這樣的事情之一後應該感到讚賞，數據標準化。