如何在 SQL 中获取过去 12 个月的特定时间窗口

Question

I am looking for a way to get a certain time window of the past 12 Months from current date.

I want to get every day from the past 12 Months but there is a specific time window in between those dates because there is a start date and an end date.

So one day would be.

SELECT startdate, enddate
     FROM TableX
      WHERE 
         startdate >= SMALLDATETIMEFROMPARTS(YEAR(GETDATE()), MONTH(GETDATE()), DAY(GETDATE()-1), 05, 00) 
     AND enddate <= SMALLDATETIMEFROMPARTS(YEAR(GETDATE()), MONTH(GETDATE()), DAY(GETDATE()), 05, 00)

That would give me yesterdays date "2021-11-14T05:00:00Z" to todays date ("2021-11-15T05:00:00Z") . Now I want this for the past 12 Months. Between yesterdays date an todays date are different timestamps that come with a specific value.

So I need to sum up every value in beetween that timestamp.

Answer 1

Using the EOMONTH function you can also calculate the start of the month for a given date.

So this

select 
 CAST(DATEADD(MONTH,-12,DATEADD(DAY,1,EOMONTH(GETDATE(),-1))) AS SMALLDATETIME) AS startDate, 
 CAST(DATEADD(DAY,1,EOMONTH(GETDATE(),-1)) AS SMALLDATETIME) AS endDate

Returns this (when run today, November 2021)

startDate	endDate
2020-11-01 00:00	2021-11-01 00:00

The query for the previous 12 months :

SELECT startdate, enddate
FROM TableX
WHERE startdate >= CAST(DATEADD(MONTH,-12,DATEADD(DAY,1,EOMONTH(GETDATE(),-1))) AS SMALLDATETIME)
  AND enddate < CAST(DATEADD(DAY,1,EOMONTH(GETDATE(),-1)) AS SMALLDATETIME)