Question

我不知道错误是从哪里来的... 我的代码中显示以下错误。我尝试搜索但未找到任何有用的东西。

从第31行开始的错误- 从Item_ID = 104的Item_Requisite中删除

错误报告- ORA-04091：表DB20168002.ITEM_REQUISITE正在变异，触发器/函数可能看不到

ORA-06512：在“ DB20168002.TR”中，第2行 ORA-04088：执行触发器'DB20168002.TR'时发生错误

drop table Item_Master;
drop table Item_Requisite;
create table Item_Master(Item_ID number primary key,Description varchar2(50),Bal_Stock number);
insert into Item_Master values(101,'keyboard',80);
insert into Item_Master values(102,'lathe_machine',70);
insert into Item_Master values(103,'compass',100);
insert into Item_Master values(104,'compass',90);
insert into Item_Master values(105,'Ammeter',60);

create table Item_Requisite(Item_ID number primary key,Dept_Code varchar2(50),Quantity number);
insert into Item_Requisite values(101,'cs',30);
insert into Item_Requisite values(102,'mech',20);
insert into Item_Requisite values(103,'civil',25);
insert into Item_Requisite values(104,'chem',35);
insert into Item_Requisite values(105,'elect',80);

create or replace trigger tr
before delete 
on
Item_Requisite
for each row
begin
    MERGE INTO Item_Master t1
    USING Item_Requisite t2
    ON (t1.Item_ID=t2.Item_ID)
    WHEN MATCHED THEN 
    UPDATE SET t1.Bal_Stock=t1.Bal_Stock-t2.Quantity
    where t1.Item_ID=104;   
end;
/
delete from Item_Requisite where Item_ID=104;
/
select * from Item_Master;

Answer 1

不要MERGE；您没有执行任何INSERT（并且MERGE被称为 upsert （在单个操作中进行更新/插入）。UPDATE将完成以下工作：< / p>

SQL> create or replace trigger tr
  2  before delete
  3  on
  4  Item_Requisite
  5  for each row
  6  begin
  7    update item_master t1 set
  8      t1.bal_stock = t1.bal_stock - :old.quantity
  9      where t1.item_id = 104
 10        and :old.item_id = t1.item_id;
 11
 12  --    MERGE INTO Item_Master t1
 13  --    USING Item_Requisite t2
 14  --    ON (t1.Item_ID=t2.Item_ID)
 15  --    WHEN MATCHED THEN
 16  --    UPDATE SET t1.Bal_Stock=t1.Bal_Stock-t2.Quantity
 17  --    where t1.Item_ID=104;
 18  end;
 19  /

Trigger created.

SQL> delete from Item_Requisite where Item_ID=104;

1 row deleted.

SQL> select * from Item_Master;

   ITEM_ID DESCRIPTION                                         BAL_STOCK
---------- -------------------------------------------------- ----------
       101 keyboard                                                   80
       102 lathe_machine                                              70
       103 compass                                                   100
       104 compass                                                    55
       105 Ammeter                                                    60

SQL>

使用更新联接触发器

1 个答案: