來自sql表的評論者的平均得分

Question

以下是我的查詢給我結果的相應值的總和。我如何計算每列預期ID的平均值？

Select 
    count(StoreId) as TotalReview, 
    sum(Case OnTimeDelivery when 'Within Time' then 1 else 0 end) as OnTimeDeliveryWithinTime, 
    sum(Case OnTimeDelivery when 'Little Delay' then 1 else 0 end) as OnTimeDeliveryLittleDelay, 
    sum(Case OnTimeDelivery when 'Excess Delay' then 1 else 0 end) as OnTimeDeliveryExcessDelay, 
from 
    StoreReviews 
where 
    StoreId = 1 

Answer 1

您需要使用GROUP BY條款

SELECT storeId, COUNT(ontimedelivery), AVG(<column>) 
FROM storereviews 
WHERE storeid=1 
GROUP BY ontimedelivery 

Answer 2

你可以得到SUM根據您自己的查詢每家商店，但你必須添加GROUP BY，如：

SELECT Storeid, COUNT(StoreId) as TotalReview, 
SUM(Case OnTimeDelivery WHEN 'Within Time' THEN 1 ELSE 0 END) as OnTimeDeliveryWithinTime, 
SUM(Case OnTimeDelivery WHEN 'Little Delay' THEN 1 ELSE 0 END) as OnTimeDeliveryLittleDelay, 
SUM(Case OnTimeDelivery WHEN 'Excess Delay' THEN 1 ELSE 0 END) as OnTimeDeliveryExcessDelay 
FROM StoreReviews 
GROUP BY Storeid 

現在，如果你想得到的平均不是爲每個商店，而是爲所有商店基於OnTimeDelivery你是否Within Time或Little Delay或Excess Delay可以使用AVG這樣的：

SELECT CONVERT(Decimal(5,2),AVG(CAST(TotalReview as float))) as AvgTotal, CONVERT(Decimal(5,2),AVG(CAST(OnTimeDeliveryWithinTime as float))) as AvgWithinTime, CONVERT(Decimal(5,2),AVG(CAST(OnTimeDeliveryLittleDelay as float))) as AvgLittleDelay, CONVERT(Decimal(5,2),AVG(CAST(OnTimeDeliveryExcessDelay as float))) as AvgExcessDelay 
FROM (
SELECT Storeid, COUNT(StoreId) as TotalReview, 
SUM(Case OnTimeDelivery WHEN 'Within Time' THEN 1 ELSE 0 END) as OnTimeDeliveryWithinTime, 
SUM(Case OnTimeDelivery WHEN 'Little Delay' THEN 1 ELSE 0 END) as OnTimeDeliveryLittleDelay, 
SUM(Case OnTimeDelivery WHEN 'Excess Delay' THEN 1 ELSE 0 END) as OnTimeDeliveryExcessDelay 
FROM StoreReviews 
GROUP BY Storeid 
) StoreAverages 

見我Fiddle Demo