Sql平均每天增加

Question

我有一个db表，它有一个日期字段，一个用户名字段和一个整数点余额字段。每天都有记录，在工作日结束时存储余额。

我正在寻找最有效的方法来计算每位用户的平均每日增幅，将最高平均每日增幅排序为最低。

Answer 1

这适用于MS SQL Server。它假设每个用户每个日期确实有一个条目，日期没有间隙，并且没有时间（小时，分钟，秒）值。 （此外，没有空值！）它将计算平均每日增加量，无论它是否实际上都在上升。

SELECT mt.UserName, avg(mt.Balance - mt2.Balance) AvgDailyIncrease
 from MyTable mt
  inner join MyTable mt2
   on mt2.UserName = mt.UserName
    and mt2.CaptureDate = dateadd(dd, -1, mt.CaptureDate)
 group by mt.UserName
 order by avg(mt.Balance - mt2.Balance) desc

Answer 2

假设余额总是增加，您可以在第一天找到余额，在最后一天找到余额，并计算平均值（基于天数）：

;with minmax as ( -- subquery to get min / max data per user
    select
        username
        ,min(capturedate) as mincapturedate
        ,min(balance) as minbalance
        ,max(capturedate) as maxcapturedate
        ,max(balance) as maxbalance
    from
        [5171722] t
    group by username
)
,averageincrease as ( -- subquery to calculate average daily increase
    select
        username
        ,datediff(day, mincapturedate, maxcapturedate) as numdays
        ,(maxbalance - minbalance) as totalincrease
        ,(maxbalance - minbalance) / datediff(day, mincapturedate, maxcapturedate) as
            averagedailyincrease
    from
        minmax
)
-- pull results together, with highest average daily increase first
select
    *
from
    averageincrease
order by
    averagedailyincrease desc

结尾处的字段averagedailyincrease包含每日平均增幅。