CREATE OR REPLACE TRIGGER<觸發(fā)器名>

CREATE TRIGGER my_trigger --定義一個觸發(fā)器my―trigger
BEFORE INSERT or UPDATE of TID,TNAME on TEACHERS
FOR each row
WHEN(new.TNAME='David') --這一部分是觸發(fā)條件
DECLARE --下面這一部分是觸發(fā)體
teacher_id TEACHERS.TID％TYPE;
INSERT_EXIST_TEACHER EXCEPTION;
BEGIN
SELECT TID INTO teacher_id
FROM TEACHERS
WHERE TNAME=new.TNAME;
RAISE INSERT_EXIST_TEACHER；
EXCEPTION --異常處理也可用在這里
WHEN INSERT_EXIST_TEACHER THEN
INSERT INTO ERROR(TID,ERR)
VALUES(teacher_id，'the teacher already exists!');
END my triqqer;

CREATE TRIGGER my_trigger1
AFTER INSERT or UPDATE or DELETE on TEACHERS
FOR each row；
DECLARE
info CHAR(10)；
BEGIN
IF inserting THEN --如果進行插入操作
info:='INSERT';
ELSIF updating THEN --如果進行修改操作
info:='Update';
ELSE--如果進行刪除操作
info:='Delete';
END IF;
INSERT INTO SQL_INFO VALUES(info); --記錄這次操作信息
END my_trigger1;

DROP TRIGGER my_trigger;