SQL if not null update

Question

I have this query

UPDATE users SET username = Param1,email = Param2,PASSWORD = Param3 WHERE id = Param4;

this is updating my user row, but

Answer 1

Please check if this works..

 DECLARE @email varchar(100), @password varchar(50)
    SET @email = null  
    SET @password = null

    IF @email <= (SELECT email from users WHERE id = Param4)   
    UPDATE users SET username = Param1,email = Param2,PASSWORD = Param3 WHERE id = Param4;

    IF @password <= (SELECT PASSWORD from users WHERE id = Param4)   
    UPDATE users SET username = Param1,email = Param2,PASSWORD = Param3 WHERE id = Param4;