SQL查詢SUM和除以不同日期計數

Question

我協助，我正在尋找數據字段的總和，然后想要除以該字段中不同日期的數量。

SUM(CASE WHEN dateResolved IS NOT NULL 
         THEN 1 ELSE 0 
    END) / DISTINCT(dateResolved) AvgPerDay

如果dateResolved中有32個日期，有5個不同的日期，我希望它返回6.4。

Answer 1

默認情況下，它需要整數除法：

SUM(CASE WHEN dateResolved IS NOT NULL 
         THEN 1 ELSE 0 
    END) * 1.0 / COUNT(DISTINCT dateResolved) AvgPerDay

然而，簡單count也會起作用：

COUNT(dateResolved) * 1.0 / COUNT(DISTINCT dateResolved) AvgPerDay

COUNT(dateResolved)將忽略null值。

Answer 2

我會這樣做：

SUM(CASE WHEN dateResolved IS NOT NULL 
         THEN 1.0 ELSE 0 
    END) / COUNT(DISTINCT dateResolved) as AvgPerDay

但這更簡單地表達為：

COUNT(dateResolved) * 1.0 / COUNT(DISTINCT dateResolved) as AvgPerDay