ON NULL?

and another little new feature of oracle 12c: ON NULL for table columns definitions

SQL> !cat a.sql
CREATE TABLE T1 ( a number
                , b varchar2(5) default on null 'aaaaa' not null );

insert into t1 ( a,b ) values ( 1,'aaaa');
insert into t1 ( a,b ) values ( 1,null);
select * from t1;

	 A B
---------- -----
	 1 aaaa
	 1 aaaaa

on null