SELECT Id, Tipo, NomeContratto, Finanziatore, RespIsti, labISTI,
       RuoloISTI, Inizio, Fine, Causale, Importo FROM (
  SELECT *, "importotot" AS Causale, ImportoTot AS Importo FROM contratti
  UNION SELECT *, "quotaISTI", QuotaISTI FROM contratti
  UNION SELECT *, "19xx", da1988e1999 FROM contratti
  UNION SELECT *, 2000, A2000 FROM contratti
  UNION SELECT *, 2001, A2001 FROM contratti
  UNION SELECT *, 2002, A2002 FROM contratti
  UNION SELECT *, 2003, A2003 FROM contratti
  UNION SELECT *, 2004, A2004 FROM contratti
  UNION SELECT *, 2005, A2005 FROM contratti
  UNION SELECT *, 2006, A2006 FROM contratti
  UNION SELECT *, 2007, A2007 FROM contratti
  UNION SELECT *, 2008, A2008 FROM contratti
  UNION SELECT *, 2009, A2009 FROM contratti
  UNION SELECT *, "totalequote", TotaleQuote FROM contratti
  UNION SELECT *, "incasso", Incasso FROM contratti
) AS tabimporti WHERE (Importo>0) ORDER BY Id;
