T-SQL, stored procedure, optional OUTPUT parameter

sp_optional_OUTPUT_parameter.sql

-- # Can I have an optional OUTPUT parameter in a stored procedure?
-- ref → http://stackoverflow.com/questions/3267523/can-i-have-an-optional-output-parameter-in-a-stored-procedure
-- Both input and output parameters can be assigned defaults. In this example:

CREATE PROCEDURE MyTest
  @Data1 int
 ,@Data2 int = 0
 ,@Data3 int = null output
AS
BEGIN
PRINT @Data1
PRINT @Data2
PRINT isnull(@Data3, -1)
SET @Data3 = @Data3 + 1
RETURN 0
END

------ demo ------
DECLARE @Output int
SET @Output = 3

EXECUTE MyTest
  @Data1 = 1
 ,@Data2 = 2
 ,@Data3 = @Output output

PRINT @Output