Thank you.

I believe that error can be detected at compile time. Is there any "good" reason they did not implement it?

My question was, as NULLLLLLL is not a valid value, why my sp compiles with no error?

You must not use CAST(... AS NVARCHAR(32)), that would remove the 2 last characters

-- with SqlServer 2005

DECLARE @md5 VARCHAR(32)

DECLARE @string varchar(10)

SET @string = 'Davolio'

SELECT

HashBytes('MD5',@string ),

master.dbo.fn_varbintohexstr(HashBytes('MD5',@string )),

SUBSTRING(master.dbo.fn_varbintohexstr(HashBytes('MD5',@string )),3,32 ),

SUBSTRING(CAST(master.dbo.fn_varbintohexstr(HashBytes('MD5',@string...