arms - 1:01 pm on Dec 28, 2012 (gmt 0)

TRY:-

CREATE TABLE CHANGES
(USER CHAR(20) NOT NULL,
CHA_TIME TIMESTAMP NOT NULL,
CHA_ISBN CHAR(20) NOT NULL,
CHA_TYPE CHAR(1) NOT NULL,
CHA_ISBN_NEW CHAR(20),
PRIMARY KEY(USER, CHA_TIME, CHA_ISBN, CHA_TYPE));

CREATE TRIGGER INSERT BOOK_INFO
AFTER
INSERT ON BOOK_INFO FOR EACH ROW
BEGIN
INSERT INTO CHANGES
(USER, CHA_TIME, CHA_ISBN, CHA_TYPE, CHA_ISBN_NEW)
VALUES(USER, CURDATE(), NEW.ISBN, 'I', NULL)
END;