Title should have read IsNull and not Is Null. However interesting effect as you found out.
Example.
declare @x varchar(5)
select isnull(@x,'1234567890')
From BOL
check_expression
Is the expression to be checked for NULL. check_expression can be of any type.
replacement_value
Is the expression to be returned if check_expression is NULL. replacement_value must have the same type as check_expresssion.
Keep in mind type is not varchar but the varchar(5). Many folks forget that.
Thank you very much for your leg work it is something difficult to spot and definitely will go into my bag of "check before release"
If you look on the Microsoft SQL Server site you will see that there is a books on-line update dated January 2004.
You can tell if you need the update by looking at the documentation for the sp_addlogin stored procedure.
If example E for copying passwords says
CONVERT(VARBINARY(32),[Password])
instead of
CONVERT(VARBINARY(256),[Password])
then you need to update BOL.
I enjoyed this article, good description of problem solving exercise.
But I don't think the title or any focus on isnull() is right.
Assume some other function was used instead of isnull--maybe upper() for the sake of argument. Still would have had same problem with truncation. The problem was with variable declaration & fact that escaping process expanded size of string.
I've seen more problems related to isnull() or lack of it than almost any other single area, but this is not one of them.
