Oracle中变异表（ORA-04091)处理方法两则

guzan

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 tablecreate 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)declarebegin  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 itORA-06512: at "DEXTER.SALES_AMOUNT_REFRESH", line 4ORA-04088: error during execution of trigger 'DEXTER.SALES_AMOUNT_REFRESH'*/

--解决办法1：可以使用自制事务来解决，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)declarebegin 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 salesdeclare  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.iyunv.com/renfengjun/article/details/18601155

           版权声明：本文为博主原创文章，未经博主允许不得转载。