Question

My Enddate is 2009-05-31 (using sql server)

@EndDate  datetime
select startdate = dateadd(mm,-12,@EndDate)

If my EndDate = 2009-05-31
with code above will my
StartDate = 31-05-2008 is my code correct?

I want my senddate to be in the month of April so

month(senddate) = month(dateadd(day,-1,dateadd(mm,-1,@EndDate))    

is my code above correct?

Answer 1

Check below

declare @EndDate  datetime
set @EndDate = '20090531'
select dateadd(mm,0,@EndDate) -- dummy
,dateadd(mm,-1,@EndDate) -- april returns 30/4
,dateadd(mm,-2,@EndDate) -- march returns 31/3
,dateadd(mm,-3,@EndDate) -- february returns 28/2

More simple

month(senddate) = month(dateadd(mm,-1,@EndDate))

example

declare @EndDate  datetime
set @EndDate = '20090531'
select month(dateadd(mm,-1,@EndDate)) -- returns 4 (april)
,month(dateadd(mm,-2,@EndDate)) -- returns 3 (march)
,month(dateadd(mm,-3,@EndDate)) -- returns 2 (february)

Start of month

declare @EndDate  datetime
set @EndDate = '20090531'
select CONVERT(VARCHAR(6),(dateadd(mm,-1,@EndDate)),112)+'01'