Function to find the Last Date of Month One Year Ago - RETURNS ERROR

Question

I've written sql code which takes a date and finds the Last Day of the Month one year ago. For example,  it takes the date '2015-04-17' and returns the date '2014-04-30'. The code works fine in a query. Now I'm trying to turn this into a function. However,
when I try to create the function I get the error:
Operand type clash: date is incompatible with int
Why is this error being returned?
Here is my function:
CREATE FUNCTION dbo.zEOM_LY_D(@Input Date)
       RETURNS date
AS
BEGIN;
  DECLARE @Result date;
  SET @Result =  convert(DATE, DATEADD(s,-1,DATEADD(mm, DATEDIFF(m,0,dateadd(m, -11, @Input)+1),0)),101)
    RETURN @Result;
END;
Thanks for any help you can give.
                 

Answer 1

Stan,
Thanks very much- that does the trick. I should have said I am using SQL 2008 so EOMONTH is not available to me. I still don't get why I got an error though, since I was treating a date like a date and not like an int.
Thanks, John
I think i found the issue but i do not know why it is causing the issue. i think may be the way dates are treated/stored internally..i think dates are stored as no of days after 0001/01/01 but cannot see how this cwould effect..may be somebody else can through
some light..... 
if you make it as datetime it will work,
if you leave it as date - eliminate adding 1...  you should prefer to use dateadd to add/substract dates.
try this to understand..
--removed the +1 in the code
declare @input date
set @input ='20150503'
select
convert(DATE, DATEADD(s,-1,DATEADD(mm,DATEDIFF(m,0,dateadd(m, -11, @Input)),0)),101)
go
--made the datatype as datetime
declare @input datetime
set @input ='20150503'
select
convert(DATE, DATEADD(s,-1,DATEADD(mm,DATEDIFF(m,0,dateadd(m, -11, @Input)+1),0)),101)
Hope it Helps!!