alter PROCEDURE cwiczenia1_wyk1
@rok as int = 1900,
@miesiac as int = NULL

AS
BEGIN

	BEGIN TRY
		IF @miesiac is null (SELECT O.OrderDate,
									OD.UnitPrice,
									OD.Quantity
								FROM Orders as O INNER JOIN [Order Details] as OD ON O.OrderID = OD.OrderID
								WHERE YEAR(OrderDate) = @rok);

	ELSE IF @miesiac NOT BETWEEN 1 AND 12
 BEGIN
	RAISERROR('Miesiac poza zakresem',17,2);
 END

 ELSE
	BEGIN

 SELECT O.OrderDate,
		OD.UnitPrice,
		OD.Quantity
		FROM Orders as O INNER JOIN [Order Details] as OD ON O.OrderID = OD.OrderID
								WHERE YEAR(OrderDate) = @rok AND
									  MONTH(OrderDate) = @miesiac;

 END
 END TRY

 BEGIN CATCH
 PRINT ' '+ERROR_MESSAGE();

 END CATCH

 END