ALTER TRIGGER [dbo].[trD_Letture]
   ON  [dbo].[LETTURE]
   for INSERT
AS 
update dbo.letture
set letture.datarif= dateadd(yyyy,-1,letture.datarif),trucco=1, letture.orarioPuntaCont=dateadd(yyyy,-1,letture.orariopuntacont),letture.orariopuntacorr=dateadd(yyyy,-1,letture.orariopuntacorr)
from inserted as I
where (year(letture.datarif)=2010 and year(letture.orarioPuntaCont)=2010) or 
  (year(letture.datarif)=2010 and year(letture.orarioPuntaCorr)=2010)