如何让存储过程返回Varchar值？

Here is my sample:

这是我的样本：

ALTER PROCEDURE EmpFirstName
    @myParam int,
    @empFName varchar(20) output
AS
BEGIN
    SET NOCOUNT ON;

    SELECT @empFName = empfname
    FROM FE_QEMP
    WHERE empno = @myParam
END
GO
ALTER PROCEDURE