oracle中创办Sequence和Trigger的SQL语句

//建Sequence

create sequence STUDENT_S
minvalue 1
maxvalue 999999999999999999999999
start with 1
increment by 1
cache 20;

//建表
CREATE TABLE STUDENT
(
?? ID INTEGER,
?? "NAME" VARCHAR2(20),
?? ADDRESS VARCHAR2(40),
?? AGE INTEGER
)

//建Trigger
CREATE OR REPLACE TRIGGER INSERTSTUDENTID
BEFORE INSERT ON STUDENT
FOR EACH ROW
BEGIN
??? SELECT STUDENT_S.NEXTVAL INTO :NEW.ID FROM DUAL;
END;