Oracle中变异表（ORA-04091)处理方法两则

Oracle中经常使用了trigger经常会出现ora-04091变异表问题，这里带来两种处理方法给大家参考。

--**** example *****
场景描述：
--1. init table

create table sales
(prod_code varchar2( 4),amount_sold number )
;

insert into sales values ( '0100',0 );

insert into sales values ( '0200',0 );

insert into sales values ( '0300',0 );

commit ;

select * from sales order by 1 ;

-- 2. 如果插入或者更新子类别，父类别的总销量必须级联更新

-- 比如 如果更新了0111 类别销量加1 那么 父类别0100 的销量必须也加上1

/* Test trigger :

create or replace trigger sales_amount_refresh

after insert on sales

for each row

when (new.amount_sold>0)

declare



begin

update sales

set amount_sold = amount_sold + :new.amount_sold

where substr(:new.prod_code, 0, length(rtrim(prod_code, '0'))) =

rtrim(prod_code, '0') ;

end ;

*/

--会产生变异表的问题

/* Test sql :

SQL> insert into sales values ('0111',1) ;



insert into sales values ('0111',1)



ORA-04091: table DEXTER.SALES is mutating, trigger/function may not see it

ORA-06512: at "DEXTER.SALES_AMOUNT_REFRESH", line 4

ORA-04088: error during execution of trigger 'DEXTER.SALES_AMOUNT_REFRESH'

*/

--解决办法1：可以使用***事务来解决，但是有bug，即无法回滚

/*

create or replace trigger sales_amount_refresh

after insert on sales

for each row

when (new.amount_sold>0)

declare

pragma autonomous_transaction ;

begin

update sales

set amount_sold = amount_sold + :new.amount_sold

where substr(:new.prod_code, 0, length(rtrim(prod_code, '0'))) =

rtrim(prod_code, '0') ;

commit ;

end ;

自治事务里面的语句不会回滚

*/

--解决办法2

使用package的集合变量记录需要变更的信息，然后使用statement级别的trigger 执行update操作，package中的变量只在session中有效

--只需要创建一个package 头即可

create or replace package pkg_vars is

type c_t is table of number index by varchar2(4 )
;

refresh_sales_list c_t ;

end ;

/

--修改行级触发器为

create or replace trigger sales_amount_refresh

after insert on sales

for each row

when (new.amount_sold> 0)

declare

begin

if length(rtrim (:new.prod_code, '0'))> 2 then

pkg_vars.refresh_sales_list(:new.prod_code) := :new.amount_sold ;

end if ;

end ;

/

--新增语句级触发器

create or replace trigger sales_amount_refresh_statement

after insert on sales

declare

ind varchar2( 4)
;

begin

ind := pkg_vars.refresh_sales_list.first ;

WHILE ind IS NOT NULL LOOP

update sales

set amount_sold
= amount_sold + pkg_vars.refresh_sales_list(ind)

where substr(ind, 0 , length( rtrim(prod_code, '0' )))
=

rtrim(prod_code, '0' ) and length(rtrim (prod_code, '0'))= 2 ;

ind := pkg_vars.refresh_sales_list.NEXT(ind);

END LOOP;

pkg_vars.refresh_sales_list.delete ;

end ;

/

如需转载，请注明出处：
http://blog.csdn.net/renfengjun/article/details/18601155