Oracle , NULLable, NULLable . NULL .
. : (id NOT NULL, name VARCHAR2(100), surname VARCHAR2(100), blah VARCHAR2(100, date_created DATE NOT NULL)
(100, NULL, NULL, NULL, '10-JAN-2000') 100, NULL, .
, , : (id NOT NULL, date_created DATE NOT NULL, name VARCHAR2(100), surname VARCHAR2(100), blah VARCHAR2(100))
(100, '10-JAN-2000', NULL, NULL, NULL) 100, - NULL .
, NULLable - , IO CPU, .