Loop each Column In Table For Using IF UPDATE () in MS SQL Trigger.

Hi, All Expert ...
I Want To Loop and Check All Column in A Table For Value Changes Using IF UPDATE () Function. But The Problem is this Function show a Error Message as "Incorrect syntax near '@StringColumn'." The Below is the Code :"
DECLARE @StringColumn nvarchar (50) DECLARE @Counter int DECLARE @ColumnCount int
SELECT @ColumnCount =(SELECT COUNT(COLUMN_NAME)                                          FROM INFORMATION_SCHEMA.COLUMNS                                      ...