mysql int null

CREATE TABLE `test` (
	`a` INT(10) NOT NULL,
	`b` INT(10) NULL DEFAULT NULL,
	PRIMARY KEY (`a`, `b`) USING BTREE
)
COLLATE='utf8_slovenian_ci'
ENGINE=MyISAM;

insert into test (a)
values(1)

in kaj pade v tabelo ? --> 1,0
ali ne bi moralo to insertirat null v stolpec b ?