SQL Update table column if parameter has value in sigle update statement

CREATE TABLE test2(clm1 INT,clm2 INT)

INSERT INTO test2 VALUES(1,1)
INSERT INTO test2 VALUES(2,2)
INSERT INTO test2 VALUES(3,3)
INSERT INTO test2 VALUES(4,4)


DECLARE @par1 INT = 100;
DECLARE @par2 INT = NULL;

UPDATE test2
SET clm1 = COALESCE(@par1,clm1)
,clm2 = COALESCE(@par2,clm2)

WHERE clm1 = 1

SELECT * FROM test2

DROP TABLE test2