How to check if variable is NULL In Stored Procedure?

Create PROCEDURE [dbo].[UpdateRecord]
(
   @empId int,
   @name varchar(200),
)

AS

DECLARE @chkName varchar(200)

SET @chkName=(SELECT TOP 1 Emp_Name FROM Employee WHERE EmpId=@empId )

IF @chkName IS NULL

BEGIN
   UPDATE Employee SET Emp_Name = @name WHERE EmpId = @empId
END