Usa i trigger.
CREATE TABLE `tbl_test` (
`GUID` char(40) NOT NULL,
`Name` varchar(50) NOT NULL,
PRIMARY KEY (`GUID`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1;
table e pk, ora trigger..
DELIMITER //
CREATE TRIGGER `t_GUID` BEFORE INSERT ON `tbl_test`
FOR EACH ROW begin
SET new.GUID = uuid();
end//
DELIMITER ;
Ora prova,
insert into tbl_test(Name) value('trigger happy...');
saluti,/t