ORACLE PL/SQL 触发器

触发器

触发器触发顺序:
---------------------------------------------------------------------------------
before
statement trigger(on table)->before row trigger (on table for each
row)->
after row trigger (on table for each row)->after statement
trigger (on table)

create or replace trigger e_update1
before update
on e
begin
if updating then
dbms_output.put_line('table
before');
end if;
end;
/

create or replace trigger
e_update2
before update on e for each row
begin
if updating
then
dbms_output.put_line('row before');
end
if;
end;
/

create or replace trigger e_update3
after update on e
for each row
begin
if updating then
dbms_output.put_line('row
after');
end if;
end;
/

create or replace trigger
e_update4
after update on e
begin
if updating
then
dbms_output.put_line('table after');
end
if;
end;
/

update e set sal=sal+1 where
empno=7369;

--验证触发器的状态
select trigger_name,status from user_triggers;
--禁用某个触发器
ALTER TRIGGER
e_update3 disable;
--禁用某个表上的所有触发器
alter table e disable all triggers;
--删除触发器
DROP TRIGGER
e_update3;

练习
1:DML触发器
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表级触发器
行级触发器

create
or replace trigger e_update
before update of sal on e
for each
row
begin
if updating then
raise_application_error(-20001,'salary do
not modify!');
end if;
end;
/

练习
2:DML触发器限制数据修改
---------------------------------------------------------------------------------
CREATE
OR REPLACE TRIGGER secure_emp
before INSERT ON e
BEGIN
IF TO_CHAR
(SYSDATE, 'HH24') NOT BETWEEN '08' AND '09'
OR TO_CHAR (SYSDATE, 'DY') IN
('SAT', 'SUN') THEN
RAISE_APPLICATION_ERROR (-20205, 'insert into table
E！');
END IF;
END;
/

练习
3:更新d表deptno时自动更新e表deptno
---------------------------------------------------------------------------------
CREATE
or replace TRIGGER vdate
AFTER UPDATE OF deptno ON d FOR EACH ROW
BEGIN
IF (UPDATING AND :old.deptno != :new.deptno) THEN --关联标识（保留结构）
UPDATE e
SET
deptno = :new.deptno
WHERE deptno = :old.deptno;
END
IF;
END;
/

练习
4:删除d表数据时自动删除e表数据
---------------------------------------------------------------------------------
CREATE
or replace TRIGGER vdate
AFTER DELETE ON d FOR EACH ROW
BEGIN
IF
DELETING THEN
delete e
WHERE deptno = :old.deptno;
END
IF;
END;
/

练习
5:删除d表数据时将e表deptno置空
---------------------------------------------------------------------------------
CREATE
or replace TRIGGER vdate
AFTER DELETE ON d FOR EACH ROW
BEGIN
IF
DELETING THEN
UPDATE e
SET deptno = :new.deptno
WHERE deptno =
:old.deptno;
END IF;
END;
/

练习
6:删除d表数据时将e表deptno置空，更新d表deptno时自动更新e表deptno
---------------------------------------------------------------------------------
CREATE
or replace TRIGGER vdate
AFTER delete or UPDATE OF deptno ON d FOR EACH
ROW
BEGIN
IF deleting or (UPDATING AND :old.deptno != :new.deptno)
THEN
UPDATE e
SET deptno = :new.deptno
WHERE deptno =
:old.deptno;
END IF;
END;
/

练习
7:删除d表数据时自动删除e表数据，更新d表deptno时自动更新e表deptno
---------------------------------------------------------------------------------
CREATE
or replace TRIGGER vdate
AFTER delete or UPDATE OF deptno ON d FOR EACH
ROW
BEGIN
IF (UPDATING AND :old.deptno != :new.deptno) THEN
UPDATE
e
SET deptno = :new.deptno
WHERE deptno = :old.deptno;
elsif deleting
then
delete e
WHERE deptno = :old.deptno;
END
IF;
END;
/

练习
8:trigger不能含有事物处理的语句!需要使用自制事务！
---------------------------------------------------------------------------------
create
or replace procedure Autonomous
(v_sal e.sal%type,v_empno
e.empno%type)
is
PRAGMA Autonomous_transaction;
--声明为自治事物
begin
update e set sal=v_sal where
empno=v_empno;
commit;
end
Autonomous;
/

--如果emp表的sal被更新那么自动更新e表的sal
create or replace trigger
cascade_update_e
before update of sal on emp for each row
declare
v_sal
e.sal%type;
v_empno e.empno%type;
begin
v_sal := :new.sal;
v_empno
:= :new.empno;
Autonomous(v_sal,v_empno);
end;
/

练习
9:系统触发器
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conn
scott/tiger
drop table log_table;
create table log_table(sid
number,
serial# number,
username varchar2(30),
action
varchar2(8),
log_time varchar2(19));

grant select on scott.log_table
to public;
grant insert on scott.log_table to
public;

--用户级别：
create or replace trigger scott_logon
after logon
on schema
declare
v_sid v$mystat.sid%type;
v_serial#
v$session.serial#%type;
v_username
v$session.username%type;
begin
select sid into v_sid from v$mystat where
rownum=1;
select serial#,username
into v_serial#,v_username
from
v$session
where sid=v_sid;
insert into scott.log_table
values
(v_sid,v_serial#,v_username,'logon',to_char(sysdate,'yyyy-mm-dd
hh24:mi:ss'));
end scott_logon;
/

create or replace trigger
scott_logof
before logoff on schema
declare
v_sid
v$mystat.sid%type;
v_serial# v$session.serial#%type;
v_username
v$session.username%type;
v_status v$session.status%type;
begin
select
sid into v_sid from v$mystat where rownum=1;
select serial#,username
into
v_serial#,v_username
from v$session
where sid=v_sid;
insert into
scott.log_table
values
(v_sid,v_serial#,v_username,'logoff',to_char(sysdate,'yyyy-mm-dd
hh24:mi:ss'));
end
scott_logof;
/

--通过用户级别触发器修改排序方法:（也可以修改语言选项或日期格式）
CONN
SCOTT/TIGER
CREATE OR REPLACE TRIGGER test_tri
AFTER LOGON ON
schema
DECLARE
sqlstr VARCHAR2(200) :=
'alter session set nls_sort = SCHINESE_STROKE_M';
BEGIN
execute immediate sqlstr;
END
test_tri;
/

--通过数据库级别触发器修改排序方法:
CONN / AS SYSDBA
CREATE OR
REPLACE TRIGGER test_tri
AFTER LOGON ON DATABASE
DECLARE
sqlstr
VARCHAR2(200) := 'alter session set nls_sort =
SCHINESE_STROKE_M';
BEGIN
IF (USER = 'SCOTT') THEN
execute immediate
sqlstr;
END IF;
END test_tri;
/

--数据库级别：得具有访问v$的权限!
conn
sys/oracle as sysdba

create or replace trigger LogSchemaConnects
after
logon on database
declare
v_sid v$mystat.sid%type;
v_serial#
v$session.serial#%type;
v_username
v$session.username%type;
begin
select sid into v_sid from v$mystat where
rownum=1;
select serial#,username
into v_serial#,v_username
from
v$session
where sid=v_sid;
insert into scott.log_table
values
(v_sid,v_serial#,v_username,'logon',to_char(sysdate,'yyyy-mm-dd
hh24:mi:ss'));
end LogSchemaConnects;
/

create or replace trigger
dbshutdown
before shutdown on database
declare
v_sid
v$mystat.sid%type;
v_serial# v$session.serial#%type;
v_username
v$session.username%type;
begin
select sid into v_sid from v$mystat where
rownum=1;
select serial#,username
into v_serial#,v_username
from
v$session
where sid=v_sid;
insert into scott.log_table
values
(v_sid,v_serial#,v_username,'ShutDown',to_char(sysdate,'yyyy-mm-dd
hh24:mi:ss'));
end dbshutdown;
/

--限制指定用户从指定IP登录:
CREATE OR
REPLACE TRIGGER TRIGGER_RESTRICT_LOGON
AFTER LOGON ON
DATABASE
DECLARE
RESTRICTED_USER VARCHAR2(32) := 'SCOTT';
ALLOWED_IP
VARCHAR2(16) := '10.1.1.244';
LOGON_USER VARCHAR2(32);
CLIENT_IP
VARCHAR2(16);
BEGIN
LOGON_USER :=
SYS_CONTEXT('USERENV','SESSION_USER');
CLIENT_IP :=
NVL(SYS_CONTEXT('USERENV','IP_ADDRESS'), 'NULL');
IF LOGON_USER =
RESTRICTED_USER AND CLIENT_IP <> ALLOWED_IP
THEN
RAISE_APPLICATION_ERROR(-20001, RESTRICTED_USER || ' is not allowed to
connect from ' || CLIENT_IP);
END IF;
END;
/

练习
10:替代触发器(由视图的dml操作所触发)
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CREATE
OR REPLACE VIEW VVV AS
SELECT E.EMPNO,E.ENAME,D.DEPTNO,D.DNAME,D.LOC
FROM
EMP E,DEPT D
WHERE E.DEPTNO=D.DEPTNO;

INSERT INTO VVV VALUES
(7777,'zjz',50,'SALES','Beijing');

CREATE OR REPLACE TRIGGER
insert_EMP_AND_DEPT
INSTEAD OF INSERT ON VVV
DECLARE
duplicate_info
EXCEPTION;
PRAGMA EXCEPTION_INIT (duplicate_info, -00001);
BEGIN
IF
INSERTING THEN
INSERT INTO DEPT (DEPTNO, DNAME, LOC)
VALUES
(
:new.DEPTNO,
:new.DNAME,
:new.LOC);
INSERT INTO EMP
(EMPNO,
ENAME, DEPTNO)
VALUES
(
:new.EMPNO,
:new.ENAME,
:new.DEPTNO);
ELSIF DELETING
THEN
NULL;
ELSE
NULL;
END IF;
EXCEPTION
WHEN duplicate_info
THEN
RAISE_APPLICATION_ERROR (
num=> -20107,
msg=> 'Duplicate EMP
or DEPT ID');
END insert_EMP_AND_DEPT

/