Sql加入平均值

我正在使用SQL Server 2012.我有兩個表來保存產品訂單。包含接收日期和OrderItem的訂單，其中包含價格和訂單ID fk。Sql加入平均值

我有一個查詢按日期對訂單進行分組，並獲取該日期的訂單數量和總價格。我還有一個7天前的訂單數量差異列。

但是，我也希望能夠在過去7天內獲得所有訂單的平均值。

因此，在目前，我有以下查詢：

declare @DateFrom datetime 
set @DateFrom = '2012-12-01' 

declare @DateTo datetime 
set @DateTo = '2013-03-13' 

;with orders as (
    select 
    cast(o.ReceivedDate as date) as OrderDate, 
    count(oi.Id) as Orders, 
    coalesce(sum(oi.Price), 0) as Price 
    from OrderItem oi 
    join [Order] o on oi.OrderId = o.Id 
    where cast(o.ReceivedDate as date) >= @DateFrom 
    and cast(o.ReceivedDate as date) <= @DateTo 
    group by cast(o.ReceivedDate as date) 
) 

select c1.OrderDate, 
c1.Price, 
c1.Orders, 
c1.Orders - c2.Orders as DIFF7DAYS 
from orders c1 
left join orders c2 on dateadd(day, -7, c1.OrderDate) = c2.OrderDate 
order by c1.OrderDate desc

現在我想補充另一列其獲得的平均訂單在過去的7天。

我已經試過類似：

select c1.OrderDate, 
c1.Price, 
c1.Orders, 
c1.Orders - c2.Orders as DIFF7DAYS, 
c3.AverageOrders 
from orders c1 
left join orders c2 on dateadd(day, -7, c1.OrderDate) = c2.OrderDate 
left join (
select OrderDate, avg(Orders) as AverageOrders 
from orders 
group by OrderDate 
) as c3 on c3.OrderDate >= dateadd(day, -7, c1.OrderDate) and c3.OrderDate <= c1.OrderDate  and c3.OrderDate = c1.OrderDate 
order by c1.OrderDate desc

但似乎並沒有這樣做我什麼。我也嘗試從連接中刪除c3.OrderDate = c1.OrderDate，但後來我得到了影響平均值的重複行。基本上我想添加一列到結果：

select avg(Orders) as AverageOrders 
from orders 
where OrderDate >= (the current order - 7 days) and OrderDate <= (the current order)

但我不知道如何做到這一點？我創建了一個sqlfiddle幫助解釋http://sqlfiddle.com/#!6/8b837/44

從我想要實現的是我的樣本數據

所以結果是這樣的：

| ORDERDATE | ORDERS | PRICE | DIFF7DAYS | AVERAGE | 
------------------------------------------------------- 
| 2013-01-25 |  7 | 38 |   6 |  2 | 
| 2013-01-24 |  2 | 12 |  null |  1 | 
| 2013-01-23 |  1 | 10 |  null |  1 | 
| 2013-01-22 |  1 | 33 |  null | 
| 2013-01-18 |  1 | 10 |  null | 
| 2013-01-10 |  1 |  3 |   -2 | 
| 2013-01-08 |  2 | 11 |  null | 
| 2013-01-04 |  1 |  1 |  null | 
| 2013-01-03 |  3 | 46 |  null |

正如你可以看到，25日的平均的2因爲最後7天（25,24,23,22,18）的四捨五入均值爲2.

我也希望能夠延長這一點，併爲30天以上的平均值添加另一列。

任何幫助將不勝感激。

來源

2013-03-18 Terry

我不是100％正面我理解您的問題，但我相信您正在嘗試SUM前7天的訂單列，併除以COUNT以獲得AVG。如果是這樣，那麼這應該用你提供的小提琴：

declare @DateFrom datetime 
    set @DateFrom = '2012-12-01' 

    declare @DateTo datetime 
    set @DateTo = '2013-03-13' 

    ;with orders as (
     select 
     cast(o.ReceivedDate as date) as OrderDate, 
     count(oi.Id) as Orders, 
     coalesce(sum(oi.Price), 0) as Price 
     from OrderItem oi 
     join [Order] o on oi.OrderId = o.Id 
     where cast(o.ReceivedDate as date) >= @DateFrom 
     and cast(o.ReceivedDate as date) <= @DateTo 
     group by cast(o.ReceivedDate as date) 
    ), 
    totals as (
     select c1.OrderDate, 
     c1.Price, 
     c1.Orders, 
     c1.Orders - c2.Orders as DIFF7DAYS, 
     ROW_NUMBER() OVER (ORDER BY c1.OrderDate DESC) rn 
     from orders c1 
     left join orders c2 on dateadd(day, -7, c1.OrderDate) = c2.OrderDate 

) 
Select t.OrderDate, t.Price, t.Orders, t.Diff7Days, 
    SUM(t2.Orders)/COUNT(t2.Orders) avg 
FROM totals t 
LEFT JOIN totals t2 on t.rn + 7 > t2.rn and t2.rn >= t.rn 
GROUP BY t.OrderDate, t.Price, t.Orders, t.Diff7Days 
order by t.OrderDate desc

SQL Fiddle Demo

如果你想爲那些不有7天的有價值數據的記錄，一個簡單的CASE語句來檢查COUNT NULL值可以確定。

來源

2013-03-18 23:20:59 sgeddes

Sql加入平均值

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