[Zope] Field type 'Date' in SQL request

[champier2002]

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