dynamic SQL : use variable declared in a string, outside of the string - sql

Question

I have a stored procedure which should calculate one's age.
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
alter PROCEDURE [dbo].[ageTest]
(
#curDate date
)
AS
BEGIN
SET NOCOUNT ON;
declare #sql nvarchar(max)
declare #params nvarchar (1000)
declare #age date
set #params = N' #curDate date , #age date output'
set #sql = '
declare #dif float
declare #ageRound int
declare #theAge varchar (100)
set #age = ''19890406''
set #theAge =(select (datediff (mm, #age , getdate())))
set #dif = #theAge % 12
set #ageRound = cast (#theAge as float)/12
select #ageRound as Years, #dif as months
'
set #sql = replace (#sql, '19890406', #curDate)
execute sp_executesql #sql, #params, #curDate, #age output
end
execute [dbo].[ageTest] '19511214'
What I want to obtain is two columns:
Years Months
63 10
Right now it looks like this:
The problem is it loops. I should probably remove the select from #sql and put it outside, then I have the declaration problem. Thoughts?
Edit: not a duplicate

Answer 1

IF you're really only a beginner.
First of all, you should always be using TRY...CATCH block in your procedures.
Here's a quick rewrite of what you've done in your code:
-- =============================================
-- Procedure Name : dbo.ageTest
-- Usage Example : EXECUTE [dbo].[ageTest] '19511214';
-- =============================================
ALTER PROCEDURE [dbo].[ageTest]
(
#curDate DATE
)
AS
BEGIN
SET NOCOUNT ON;
BEGIN TRY
SELECT DATEDIFF(MM, #curDate, CURRENT_TIMESTAMP) / 12 AS Years
, DATEDIFF(MM, #curDate, CURRENT_TIMESTAMP) % 12 AS Months;
END TRY
BEGIN CATCH
SELECT ERROR_NUMBER(), ERROR_MESSAGE();
END CATCH
END
It shows how you should be using parameters in SP.