(PHP 4 >= 4.0.2, PHP 5)
ingres_field_nullable() returns TRUE if the field can be set to the NULL value and FALSE if it can't.
index is the number of the field and must be between 1 and the value given by ingres_num_fields().
See also ingres_query(), ingres_fetch_array(), ingres_fetch_object() and ingres_fetch_row().
