SQL划分的平均值

Question

我正在尝试获取SQL中比率的平均值。

我的表看起来像这样：

T_TOTAL | NUM_ASSETS 
---------------------- 
    32 |  8 
    20 |  4 
    24 |  4 

而且使价值我后为：

T_TOTAL | NUM_ASSETS | T_TOTAL/NUM_ASSETS 
--------------------------------------------- 
    32 |  8  |   4 
    20 |  4  |   5 
    24 |  4  |   6 
          ------------------- 
          AVG = 5 

到目前为止，我有这个，但它不工作：

SELECT T_TOTAL As Time, NUM_ASSETS As Assets, 
Time/Assets As TimePerAsset, AVG(TimePerAsset) As Result 
FROM MATCHES 

任何想法？

Answer 1

select avg(t_total/num_assets) from matches 

而且，如果您NUM_ASSETS有0，则可以通过0避免分工是这样的：

select avg(t_total/nullif(num_assets, 0)) from matches 

Answer 2

你可以试试这个

SELECT T_TOTAL As Time, NUM_ASSETS As Assets, 
case when Assets <> 0 then Time/Assets end As TimePerAsset, AVG(case when Assets <> 0 then Time/Assets end) As Result 
FROM MATCHES 

Answer 3

SELECT M.Time, M.Assets, M.TimePerAsset, Avg(M.TimePerAsset) as AvgTimePerAsset 
FROM 
(
    SELECT T_TOTAL As TotalTime 
     , NUM_ASSETS As Assets 
     , CASE WHEN NUM_ASSETS <> 0 THEN T_TOTAL/NUM_ASSETS ELSE NULL END As TimePerAsset 
    FROM Matches 
) M 
GROUP BY M.Time, M.Assets, M.TimePerAsset 

Answer 4

SELECT t.*, 
     Result = AVG(TimePerAsset) 
    FROM (
      SELECT [Time] = T_TOTAL, 
        [Assets] = NUM_ASSETS, 
        [TimePerAsset] = CASE WHEN NUM_ASSETS <> 0 
              THEN T_TOTAL/NUM_ASSETS 
              ELSE NULL 
            END 
       FROM MATCHES 
     ) t