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Oracle中触发器（2）
上一篇对触发器的一些基本知识有了了解，在这一篇操作进行验证
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before触发器
[oracle@test ~]$ sqlplus / as sysdba
SQL> create user trigger_test identified by 123456 ; SQL> grant create session to trigger_test ; SQL> grant create table to trigger_test ; SQL> grant dba to trigger_test ; SQL> grant resource to trigger_test ； SQL> grant create sequence to trigger_test ;
[oracle@test ~]$ sqlplus trigger_test/123456
创建测试表student
SQL> create table student(STUDENT_ID NUMBER(8),name varchar2(15),CREATED_BY VARCHAR2(30) not null,CREATED_DATE DATE not null,MODIFIED_BY VARCHAR2(30) not null,MODIFIED_DATE DATE not null)
创建序列student_id_seq
create sequence student_id_seq minvalue 1 maxvalue 9999999999999999999999999999 start with 100 increment by 1;
SQL> select * from student ; no rows selected SQL> select * from cat ; TABLE_NAME TABLE_TYPE ------------------------------ ----------- STUDENT TABLE STUDENT_ID_SEQ SEQUENCE
create or replace trigger student_before_insert before insert on student for each row declare v_student_id student.student_id%type ; begin select student_id_seq.nextval into v_student_id from dual ; :new.student_id := v_student_id ; :new.created_by := user ; :new.created_date := sysdate ; :new.modified_by := user ; :new.modified_date := sysdate ; end;
SQL> insert into student (name) values ('mjt');
SQL> commit ;
SQL> select * from student ;
STUDENT_ID NAME CREATED_BY CREATED_DATE
---------- --------------- ------------------------------ -------------------
MODIFIED_BY MODIFIED_DATE
------------------------------ -------------------
100 mjt TRIGGER_TEST 2015-07-29 20:51:19
TRIGGER_TEST 2015-07-29 20:51:19
SQL> insert into student (name) values ('cxq') ;
1 row created.
SQL> select * from student ;
STUDENT_ID NAME CREATED_BY CREATED_DATE
---------- --------------- ------------------------------ -------------------
MODIFIED_BY MODIFIED_DATE
------------------------------ -------------------
100 mjt TRIGGER_TEST 2015-07-29 20:51:19
TRIGGER_TEST 2015-07-29 20:51:19
101 cxq TRIGGER_TEST 2015-07-29 21:00:54
TRIGGER_TEST 2015-07-29 21:00:54after触发器
SQL> create table record(table_name varchar2(30),transaction_name varchar2(10),transaction_user varchar2(30),transaction_date date);
这个表被用来记录数据库中不同表的信息，如，可以记录谁从student表中删除或者更新数据，以及记录时间。
下面的触发器针对对student表的更新或者删除操作，在此之后进行触发
create or replace trigger student_aud
after update or delete on student
declare
v_type varchar2(10);
begin
if updating then
v_type := 'UPDATE';
elsif deleting then
v_type := 'DELETE';
end if;
update trigger_test.record
set transaction_user = user,
transaction_date = sysdate
where table_name = 'student'
and transaction_name = v_type;
if sql%notfound then
insert into trigger_test.record values ('student', v_type, user, sysdate);
end if;
end;SQL> select * from record ; no rows selected SQL> select * from student ; STUDENT_ID NAME CREATED_BY CREATED_DATE ---------- --------------- ------------------------------ ------------------- MODIFIED_BY MODIFIED_DATE ------------------------------ ------------------- 100 mjt TRIGGER_TEST 2015-07-29 20:51:19 TRIGGER_TEST 2015-07-29 20:51:19 101 cxq TRIGGER_TEST 2015-07-29 21:00:54 TRIGGER_TEST 2015-07-29 21:00:54 SQL> update student set name = 'somebody' where name = 'mjt' ; 1 row updated. SQL> commit ; Commit complete. SQL> select * from student ; STUDENT_ID NAME CREATED_BY CREATED_DATE ---------- --------------- ------------------------------ ------------------- MODIFIED_BY MODIFIED_DATE ------------------------------ ------------------- 100 somebody TRIGGER_TEST 2015-07-29 20:51:19 TRIGGER_TEST 2015-07-29 20:51:19 101 cxq TRIGGER_TEST 2015-07-29 21:00:54 TRIGGER_TEST 2015-07-29 21:00:54 SQL> select * from record ; TABLE_NAME TRANSACTIO TRANSACTION_USER ------------------------------ ---------- ------------------------------ TRANSACTION_DATE ------------------- student UPDATE TRIGGER_TEST 2015-07-29 21:50:46 SQL> delete student where name = 'somebody' ; 1 row deleted. SQL> commit ; Commit complete. SQL> select * from student ; STUDENT_ID NAME CREATED_BY CREATED_DATE ---------- --------------- ------------------------------ ------------------- MODIFIED_BY MODIFIED_DATE ------------------------------ ------------------- 101 cxq TRIGGER_TEST 2015-07-29 21:00:54 TRIGGER_TEST 2015-07-29 21:00:54 SQL> select * from record ; TABLE_NAME TRANSACTIO TRANSACTION_USER ------------------------------ ---------- ------------------------------ TRANSACTION_DATE ------------------- student UPDATE TRIGGER_TEST 2015-07-29 21:50:46 student DELETE TRIGGER_TEST 2015-07-29 21:56:08 SQL> alter trigger student_aud disable ; Trigger altered. SQL> update student set name = 'mjt' where name = 'cxq'; 1 row updated. SQL> commit ; Commit complete. SQL> select * from student ; STUDENT_ID NAME CREATED_BY CREATED_DATE ---------- --------------- ------------------------------ ------------------- MODIFIED_BY MODIFIED_DATE ------------------------------ ------------------- 101 mjt TRIGGER_TEST 2015-07-29 21:00:54 TRIGGER_TEST 2015-07-29 21:00:54 SQL> select * from record ; TABLE_NAME TRANSACTIO TRANSACTION_USER ------------------------------ ---------- ------------------------------ TRANSACTION_DATE ------------------- student UPDATE TRIGGER_TEST 2015-07-29 21:50:46 student DELETE TRIGGER_TEST 2015-07-29 21:56:08
禁用触发器之后，在student表上的update操作不再触发产生记录到record表
对应启用
SQL> alter trigger student_aud enable ; Trigger altered.
3.自治事务
自治事务是由其他事务(通常被称为主事务)发起的独立事务，自治事务也许会执行多个dml语句，并且提交或者回滚，而不会提交或者回滚主事务执行的dml语句。
假如希望即使主事务失败，仍旧能够记录审计数据，这种情况下，主事务是面向
表的update或者delete，需要定义可以独立于主事务进行提交的自治事务。
定义主事务，需要使用autonomous_transaction编译指令在语句块的声明部分
declare
pragma autonomous_transaction
commit ;
create or replace trigger student_aud
after update or delete on student
declare
v_type varchar2(10);
pragma autonomous_transaction ;
begin
if updating then
v_type := 'UPDATE';
elsif deleting then
v_type := 'DELETE';
end if;
update trigger_test.record
set transaction_user = user,
transaction_date = sysdate
where table_name = 'student'
and transaction_name = v_type;
if sql%notfound then
insert into trigger_test.record values ('student', v_type, user, sysdate);
end if;
commit ;
end;如果当前更新或者删除表student中的内容，无论成功或者失败，都会在record表中记录当前的操作。不足的是，record表中最多只能记录两条数据，只是当前最新操作的时间以及操作者。
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