SQL Server：上个月的5天移动平均值

Question

我有两列TOTAL和DATE的视图，后者不包括星期六和星期日，即

TOTAL      DATE
 0         1-1-2014
33         2-1-2014
11         3-1-2014
55         5-1-2014
... 
25         15-1-2014
35         16-1-2014
17         17-1-2014
40         20-1-2014
33         21-1-2014
...

我要完成的任务是计算整个月的平均5天，即在第13和第17，第14和第20（我们跳过周末），第15和第21等等，直至当前日期。 是的，它们是重叠的范围。

知道如何在SQL中实现它吗？

输出示例（从第6位开始并使用假数字）

 5daysAVG        Start_day
 22               1-01-2014   <-counted between 1st to 6th Jan excl 4 and 5 of Jan
 25               2-01-2014   <- Counted between 2nd to 7th excluding 4 and 5
 27               3-01-2014   <- 3rd to 8th excluding 4/5
 24               6-01-2014   <-6th to 10th
 ...
 33               today-5

Answer 1

好的，我通常会设置一些测试数据。

以下是在tempdb中创建[work]表的一些代码。我正在跳过周末。总数是从0到40的随机数。

-- Just playing
use tempdb;
go

-- drop existing
if object_id ('work') > 0
drop table work
go

-- create new
create table work
(
  my_date date,
  my_total int
);
go

-- clear data
truncate table work;
go

-- Monday = 1 
SET DATEFIRST 1;
GO

-- insert data
declare @dt date = '20131231';
declare @hr int;
while (@dt < '20140201')
begin
  set @hr = floor(rand(checksum(newid())) * 40);
  set @dt = dateadd(d, 1, @dt);
  if (datepart(dw, @dt) < 6)
    insert into work values (@dt, @hr);
end
go

使用新的LEAD（）窗口函数在SQL SERVER 2012中变得非常简单。

-- show data
with cte_summary as
(
select 
  row_number() over (order by my_date) as my_num,
  my_date, 
  my_total,
  LEAD(my_total, 0, 0) OVER (ORDER BY my_date) +
  LEAD(my_total, 1, 0) OVER (ORDER BY my_date) +
  LEAD(my_total, 2, 0) OVER (ORDER BY my_date) +
  LEAD(my_total, 3, 0) OVER (ORDER BY my_date) +
  LEAD(my_total, 4, 0) OVER (ORDER BY my_date) as my_sum,
  (select count(*) from work) as my_cnt
from work 
)
select * from cte_summary 
where my_num <= my_cnt - 4

基本上，我们为每一行提供一个行号，计算行0（当前）到行4（4离开）的总和以及总计数。

由于这是五个期间的运行总计，因此剩余的日期缺少数据。因此，我们把它们抛弃了。 my_row＆lt; = my_cnt -4

我希望这能解决你的问题！

如果您只关心当月的一个号码，请将选择更改为以下内容。我离开了其他行，让你了解发生了什么。

select avg(my_sum/5) as my_stat
from cte_summary 
where my_num <= my_cnt - 4

FOR SQL SERVER＆lt; 2012年＆amp; ＆gt; = 2005

就像这个世界上的任何事物一样，总有办法做到这一点。我使用一个小的计数表来循环数据并收集5个数据点的平均值。

-- show data
with
cte_tally as
(
select 
    row_number() over (order by (select 1)) as n
from 
    sys.all_columns x 
),
cte_data as
(
select 
    row_number() over (order by my_date) as my_num,
    my_date, 
    my_total 
from 
    work 
)
select 
  (select my_date from cte_data where my_num = n) as the_date,
  (
    select sum(my_total) / 5 
    from cte_data 
    where my_num >= n and my_num < n+5
  ) as the_average
from cte_tally
where n <= (select count(*)-4 from work) 

以下是常用表格式（CTE）的说明。

cte_data = order data by date and give row numbers
cte_tally = a set based counting algorithm

对于五人小组计算平均值并显示日期。

此解决方案不依赖于假期或周末。如果有数据，它只按日期按五个组分组。

如果您需要过滤假期和周末，请创建假期表。在cte_data中添加一个where子句，用于检查NOT IN（SELECT HATE FROM HOLIDAY TABLE）。

祝你好运！

Answer 2

SQL Server提供datepart(wk, ...)函数来获取一年中的一周。不幸的是，它使用一年中的第一天来定义年份。

相反，您可以找到连续值的序列并将它们组合在一起：

select min(date), max(date, avg(total*1.0)
from (select v.*, row_number() over (order by date) as seqnum
      from view
     ) v
group by dateadd(day, -seqnum, date);

这个想法是从连续几天的序列中减去一系列数字会产生一个常数。

您也可以使用规范日期并除以7来执行此操作：

select min(date), max(date, avg(total*1.0)
from view v
group by datediff(day, '2000-01-03', date) / 7;

日期'2000-01-03'是一个任意星期一。

编辑：

您似乎想要5天移动平均线。由于周末缺少数据，avg()应该可以正常工作：

select v1.date, avg(v2.value)
from view v1 join
     view v2
     on v2.date >= v1.date and v2.date < dateadd(day, 7, v1.date)
group by v1.date;

Answer 3

这是一个适用于SQL 2008的解决方案;

这里的概念是使用表变量来首先规范化数据;其余的是简单的数学计算和平均天数。

通过规范化数据，我的意思是，摆脱周末时间，并在一个临时表变量中分配ID，该变量可用于识别行;

检查出来：（SqlFiddle also here）

-- This represents your original source table
Declare @YourSourceTable Table 
(
    Total Int, 
    CreatedDate DateTime
)

-- This represents some test data in your table with 2 weekends
Insert Into @YourSourceTable Values (0, '1-1-2014')
Insert Into @YourSourceTable Values (33, '1-2-2014')
Insert Into @YourSourceTable Values (11, '1-3-2014')
Insert Into @YourSourceTable Values (55, '1-4-2014')
Insert Into @YourSourceTable Values (25, '1-5-2014')
Insert Into @YourSourceTable Values (35, '1-6-2014')
Insert Into @YourSourceTable Values (17, '1-7-2014')
Insert Into @YourSourceTable Values (40, '1-8-2014')
Insert Into @YourSourceTable Values (33, '1-9-2014')
Insert Into @YourSourceTable Values (43, '1-10-2014')
Insert Into @YourSourceTable Values (21, '1-11-2014')
Insert Into @YourSourceTable Values (5, '1-12-2014')
Insert Into @YourSourceTable Values (12, '1-13-2014')
Insert Into @YourSourceTable Values (16, '1-14-2014')

-- Just a quick test to see the source data
Select * From @YourSourceTable

/*  Now we need to normalize the data; 
    Let's just remove the weekends and get some consistent ID's to use in a separate table variable
    We will use DateName SQL Function to exclude weekend days while also giving 
    sequential ID's to the remaining data in our temporary table variable,
    which are easier to query later 
*/

Declare @WorkingTable Table 
(
    TempID Int Identity, 
    Total Int, 
    CreatedDate DateTime
)

-- Let's get the data normalized:
Insert Into 
    @WorkingTable
Select 
    Total,  
    CreatedDate
From @YourSourceTable
Where DateName(Weekday, CreatedDate) != 'Saturday' 
    And DateName(Weekday, CreatedDate) != 'Sunday' 

-- Let's run a 2nd quick sanity check to see our normalized data
Select * From @WorkingTable

/*  Now that data is normalized, we can just use the ID's to get each 5 day range and
    perform simple average function on the columns; I chose to use a CTE here just to
    be able to query it and drop the NULL ranges (where there wasn't 5 days of data)
    without having to recalculate each average
*/

; With rangeCte (StartDate, TotalAverage)
As
(
    Select
        wt.createddate As StartDate,
        (
            wt.Total +  
            (Select Total From @WorkingTable Where TempID = wt.TempID + 1) +
            (Select Total From @WorkingTable Where TempID = wt.TempID + 2) +
            (Select Total From @WorkingTable Where TempID = wt.TempID + 3) +
            (Select Total From @WorkingTable Where TempID = wt.TempID + 4)
        ) / 5
        As TotalAverage
From 
    @WorkingTable wt    
)
Select 
    StartDate,
    TotalAverage
From rangeCte
Where TotalAverage 
    Is Not Null