calculate financial periods into temp table

Question

I have a client who reports on 13 27 day periods in the financial year and I am trying to work out some dynamic SQL to identify what reporting period an invoice was raised in.

This is what I have so far but the while loop is crashing after the first loop.

IF OBJECT_ID('#Periods', 'U') IS NOT NULL
drop table #Periods

create table #Periods
([start_date] date, [end_date] date, Period varchar(3) )

declare @LYdt datetime,
        @CYdt datetime,
        @Period int

SET @Period = 0
SET @LYdt = '09/01/2016'
SET @CYdt = '09/01/2017'
While @Period  <=13

insert #Periods
select 
[Start_Date] = dateadd(mm,datediff(mm,'',@LYdt),'') - datepart(dw,dateadd(mm,datediff(mm,'',@LYdt),'')+0)+ 22,
[End Date] = (dateadd(mm,datediff(mm,'',@LYdt),'') - datepart(dw,dateadd(mm,datediff(mm,'',@LYdt),'')+0)+ 22)+27,
[Period] = 'P'+ convert(varchar(2),@Period)



SET @Period = @Period + 1
SET @LYdt =  dateadd(d,27,@LYdt)
SET @CYdt = dateadd(d,27,@CYdt)

Can anyone assist with where I have gone wrong please?

Dave

addiditonal: sample result set of sql will look like this:

Answer 1

despite agreeing with you guys that they need to provide the dates for me to work with, I couldn't let the task beat me so I have finally written up an answer that works.

It combines a scalar function for concatenating dates that I found here (Thanks to Brian for the function):

Create a date with T-SQL

With Gordons Code from above

to get the final product:

declare @LY datetime,
        @TY datetime,
        @FD datetime,
        @TY_DATE datetime,
        @LY_DATE datetime,
        @FD_DATE datetime,
        @Use_date datetime

select @LY = dbo.datemaker(datepart(year,getdate())-2, 9, 1)
select @TY = dbo.datemaker(datepart(year,getdate())-1, 9, 1)
Select @FD = dbo.datemaker(datepart(year,getdate()), 9, 1)
 select @LY_DATE =  dateadd(mm,datediff(mm,'',@LY),'') - datepart(dw,dateadd(mm,datediff(mm,'',@LY),'')+0)+ 22
 select @TY_DATE = dateadd(mm,datediff(mm,'',@TY),'') - datepart(dw,dateadd(mm,datediff(mm,'',@TY),'')+0)+ 22
 select @FD_DATE = dateadd(mm,datediff(mm,'',@FD),'') - datepart(dw,dateadd(mm,datediff(mm,'',@FD),'')+0)+ 22

select @use_date = case when(convert(date,getdate()) >= @FD_DATE) then @TY_DATE ELSE @LY_DATE END;



with periods as (
      select @use_date as start_date, 1 as lev
      union all
      select dateadd(day, 28, start_date), lev + 1
      from periods
      where start_date < dateadd(year,1,start_date) and
      lev <=12)



select start_date as [Start_Date],
       dateadd(day, 27, start_date) as end_date,
       'P' + right('00' + cast(lev as varchar(255)), 2) +'LY' as period_num

from periods

union all

select dateadd(year,1,start_date) as [Start_Date],
       dateadd(year,1,dateadd(day, 27, start_date)) as end_date,
       'P' + right('00' + cast(lev as varchar(255)), 2) +'TY' as period_num



from periods;

CREATE FUNCTION [dbo].[Datemaker]
(
    @Year INT,
    @Month INT,
    @DayOfMonth INT

)
RETURNS DATETIME
AS
BEGIN

    RETURN 
            DATEADD(day, @DayOfMonth - 1, 
            DATEADD(month, @Month - 1, 
            DATEADD(Year, @Year-1900, 0)))

END

GO

Thanks to all of you for contributing.

Regards,

Dave