'If there are more than one table, the fieldname must not be ambigous.
If the fieldname is not explicitly mentioned, set the default table'

def set_field_tables(self):

    if (len(self.tables) > 1):
        for (i, f) in enumerate(self.fields):
            if (u'.' not in f):
                self.fields[i] = u'{0}.{1}'.format(self.tables[0], f)
