SQL for calculating the sum in the past 24 months and above

Question

I want to calculate the sum and average of my data in the past 24 months how can I achieve that? In my database I have 1000 records with the field (ID, Store_ID, Date, Sales) I want to calculate the average of all my data from THIS month up to the last 24 months.

Answer 1

I believe you are looking for the DATEADD function. Here is the documentation .

Essentially, you will use a where condition to check if a date is older than a certain date.

By using the DATEADD function with the current time, you can create a date X months in the past.

SELECT columns FROM table WHERE date < DATEADD(month, numberOfMonths, GETDATE());

For SQL querys that use aggregate functions (such as SUM ), depending on how you use the function you may require the HAVING clause; instead of, the WHERE clause. I don't think your case will require this; but, I may be wrong.

You can read more on HAVING vs WHERE at this article .

Here is an example:

SELECT columns FROM table HAVING date < DATEADD(month, numberOfMonths, GETDATE());

The code samples are untested; however, the general structure is there. We are also using the GETDATE() function to get the current database date.

Answer 2

Please find below SQL where I am getting last 12 month sum of members for a given group in X table.

You can use the similar approach with some modification to below code snippet as per actual table structure to find out desired result set.

;with tbl1
as
(
    select MonthID,count(MemberID) as RecCount from MemberTable a with (nolock) group by MonthID 
)
,tbl2
as
(
    select 
        ROW_NUMBER() OVER(order by MonthID) as RowID
        ,MonthID
        ,sum(RecCount) over(order by MonthID ROWS BETWEEN 11 PRECEDING and CURRENT ROW) as [SumLast12Months] 
    from tbl1   
)
select * from tbl2 where RowID>=12 -- Before RowID 12 none of the month has complete 12 month rollup

Answer 3

Here are a couple of other options:

select sum(Sales) as [Total Sales], avg(Sales) as [Average Sales]
from (select * from @tbl where dt >= dateadd(mm, -24, getdate())) as foo

or

with CTE
as
(
    select * from @tbl where dt >= dateadd(mm, -24, getdate())
)
select sum(Sales) as [Total Sales], avg(Sales) as [Average Sales] from CTE