Assuming that you only need to compare two years, here's something that can work:
CREATE TABLE #SalesData (
    CustID char(3),
    FiscalYear smallint,
    FiscalPeriod tinyint,
    SalesQty int,
    SalesValue decimal(11,2)
);
INSERT...

I'll go ahead and reformat them all:
UPDATE KCRM
SET KCRM.IdRapportoMobile = @IdRapporto
FROM KilometriCantiereRapportoMobile AS KCRM
WHERE KCRM.IdKilometri IN (
    SELECT K.IdKilometri
    FROM Kilometri AS K
        INNER JOIN...