oracle 标准触发器的例子 笔记
-- 触发器
-- before 语句触发器
--create or replace trigger tr_src_emp
-- before insert or update or delete on emp
--begin
-- if to_char(sysdate,'DY','nls_date_language=AMERICAN') in ('SAT','SUN') then
-- raise_application_error(-20001,'can't modify user information in weekend');
-- end if;
--end;
-- 使用条件谓语
create or replace trigger tr_src_emp
before insert or update or delete on emp
begin
if to_char(sysdate,'DY') in ('星期六','星期天') then
case
when inserting then
raise_application_error(-20001,'fail to insert');
when updating then
raise_application_error(-20001,'fail to update');
when deleting then
raise_application_error(-20001,'fail to delete');
end case;
end if;
end;
-- after 语句触发器
Create table audit_table(Name varchar2(20),ins int,upd int,del int,starttime date,endtime date);
Create or replace trigger tr_audit_emp After insert or update or delete on emp
Declare
v_temp int;
Begin
Select count(*) into v_temp from audit_table
Where name='EMP';
If v_temp=0 then
Insert into audit_table values('EMP',0,0,0,sysdate,null);
End if;
Case
When inserting then
Update audit_table set ins=ins+1,endtime=sysdate where name='EMP';
When updating then
Update audit_table set upd=upd+1,endtime=sysdate where name='EMP';
When deleting then
Update audit_table set del= del +1,endtime=sysdate where name='EMP';
End case;
End;
-- before 行触发器
create or replace trigger tr_emp_sal
before update of sal on emp
for each row
begin
if :new.sal < :old.sal then
raise_application_error(-200010,'sal should not be less');
end if;
end;
-- after 行触发器
Create table audit_emp_change(
Name varchar2(10),
Oldsal number(6,2),
Newsal number(6,2),
Time date
);
Create or replace trigger tr_sal_sal
after update of sal on emp
for each row
declare v_temp int;
begin
select count(*) into v_temp from audit_emp_change where name=:old.ename;
if v_temp=0 then
insert into audit_emp_change values(:old.ename,:old.sal,:new.sal,sysdate);
else
update audit_emp_change set oldsal=:old.sal,newsal=:new.sal,time=sysdate where name=:old.ename;
end if;
end;
-- 限制行触发器
Create or replace trigger tr_sal_sal
after update of sal on emp
for each row
when (old.job='SALESMAN')
declare v_temp int;
begin
select count(*) into v_temp from audit_emp_change where name=:old.ename;
if v_temp=0 then
insert into audit_emp_change values(:old.ename,:old.sal,:new.sal,sysdate);
else
update audit_emp_change set oldsal=:old.sal,newsal=:new.sal,time=sysdate where name=:old.ename;
end if;
end;