大家好，又见面了，我是你们的朋友全栈君。
1.DML触发器
由对表的INSERT,DELETE,UPDATE激发
CREATE OR REPLACE TRIGGER trigger_name
AFTER — TIMING :BEFORE OR AFTER
DELETE OR INSERT OR UPDATE ON table_name — STATEMENT
–REFERENCING :new a :old b — new，语句后的表，old，语句前的表
FOR EACH ROW — LEVEL，行级
BEGIN
–PL/SQL
IF INSERTING THEN
insert into AUDIT_STUDENT
values
(sysdate, :new.id, :new.name, ‘INSERT’);
ELSIF DELETING THEN
insert into AUDIT_STUDENT
values
(sysdate, :old.id, :old.name, ‘DELETE’);
ELSE
insert into AUDIT_STUDENT
values
(sysdate, :old.id, :old.name, ‘UPDATE’);
END IF;
END;
/
/*DML触发器执行顺序
a.BEFORE语句级
b.BEFORE行级
c.AFTER行级
d.AFTER语句级
*/
语句级触发器：在语句执行前或执行后被触发
行级触发器：在每个触发语句影响的行触发一次，
2.INSTEAD OF触发器
代替直接对视图的INSERT,DELETE,UPDATE操作
CREATE OR REPLACE TRIGGER VW_STU_COURSE_INSERT
INSTEAD OF INSERT ON VW_STU_COURSE
FOR EACH ROW
DECLARE
rowcnt number;
BEGIN
INSERT INTO stu_info(id,name)
values(:new.id,:new.name);
insert into course_info(course_no,course_name)
values(:new.course_no,:new.course_name);
END;
/
3.系统触发器
a.DDL事件(CREATE,ALTER,DROP语句),需要有ADMISTRATER,DATABASE,TRIGGER特权
b.数据库事件
服务器启动,关闭
用户登录,注销
服务器错误等
CREATE OR REPLACE TRIGGER LogUser2Connects
AFTER LOGON ON DATABASE
BEGIN
INSERT INTO logon_record
values(sysdate,ora_login_user);
END;
/
–Enabling And Disabling Triggers
–Enabling Triggers
ALTER TRIGGER REORDER ENABLE;
ALTER TABLE INVENTORY ENABLE ALL TRIGGERS;
–Enabling Triggers
ALTER TRIGGER REORDER DISABLING;
ALTER TABLE INVENTORY DISABLING ALL TRIGGERS;
–View Of Triggers
USER_TRIGGERS
ALL_TRIGGERS
DBA_TRIGGERS
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