Calculate fiscal year in SQL Server

Question

How would you calculate the fiscal year from a date field in a view in SQL Server?

Answer 1

I've extended the answer posted by ChrisF and Conficker.

DECLARE @FFYStartMonth INT = 10 --The first month of the FFY
DECLARE @EntryDate DATETIME = '4/1/2015' --The date of the data
DECLARE @StartDate DATETIME

DECLARE @EndDate DATETIME

SET @StartDate = DATEADD(dd, 0,
    DATEDIFF(dd, 0,
        DATEADD(mm, - (((12 + DATEPART(m, @EntryDate)) - @FFYStartMonth)%12), @EntryDate) -
datePart(d,DATEADD(mm, - (((12 + DATEPART(m, @EntryDate)) - @FFYStartMonth )%12),
    @EntryDate )) + 1 ))  

SET @EndDate = DATEADD(SS, -1, DATEADD(mm, 12, @StartDate))

SELECT @StartDate, @EndDate