Return data from specified time interval in all rows in a calculated column

[souvik900766]

Hi !

My Data:-

Year	Month	CY	2018
2019	Jan, 19	784003.62
2020	Jan, 20	796922.99
2021	Jan, 21	912686.25
2018	Jan, 18	754578.30

I want to return year 2018 CY Value i.e. 754578 in 2018 Column in all rows.
The calculation should be based on latest month for e.g.
MAX(Month),dateadd(month,-3,year)
So, here I want to find from Jan, 2021, to 3 years prior data.

Thanks in advance !

[lbendlin]

@souvik900766 please post your sample data again, something seems to be missing