Here's a setup to play with including some tests to check whether a sproc will be fired or not.

USE tempdb

GO

if object_id('temp','U') is not null drop table temp

CREATE TABLE temp( idCourse INT, Libelle VARCHAR(300))

GO

CREATE TRIGGER compare

ON temp

INSTEAD OF UPDATE

AS

BEGIN

-- check if there is one single row where the value of column Libelle has changed

IF EXISTS

(

SELECT 1

FROM DELETED d

INNER JOIN INSERTED i ON i.idCourse = d.idCourse

WHERE i.Libelle <> d.Libelle

)

BEGIN

PRINT 'FIRE STORE PROCEDURE'

END

ELSE

BEGIN

PRINT 'NOT FIRE STORED PROCEDURE'

END

END

GO

INSERT INTO temp

SELECT 1,'1' UNION ALL

SELECT 2,'2'

UPDATE temp

SET Libelle = Libelle+1

UPDATE temp

SET Libelle = Libelle+1

WHERE idCourse = 2

UPDATE temp

SET Libelle = Libelle

WHERE idCourse = 2

UPDATE temp

SET Libelle = Libelle+1

WHERE idCourse = 3