Question

我正在尝试获取SQL中比率的平均值。

我的表格如下：

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

所以我所追求的价值 5 ，如：

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，但它不起作用：

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

有什么想法吗？

Answer 1

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

Answer 2

select avg(t_total/num_assets) from matches

如果num_assets中有0，则可以避免除以0，如下所示：

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

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

SQL除法的平均值

4 个答案: