[Zope] Field type 'Date' in SQL request

Hi, The application has a link with an Oracle database. In the SQL table the field is defined like this : DATE_NAI_IND DATE with NULL When I try to use this field in a SQL request, for example : select DATE_NAI_IND, COD_ETU from VUE_TRAV_EXT_RVM_RES where TO_CHAR(DATE_NAI_IND,'dd/mm/yy')= "08/08/1997" or DATE_NAI_IND = "08/08/1997" I always receive the same error : Error, dco2.DatabaseError: (904, 'ORA-00904: Nom de colonne non valide') Thanks for your help