是否有可能设计一个修改相同表（保证不相同行）的Oracle触发器？_Oracle_Plsql_Triggers

是否有可能设计一个修改相同表（保证不相同行）的Oracle触发器？

oracle plsql triggers

是否有可能设计一个修改相同表（保证不相同行）的Oracle触发器？,oracle,plsql,triggers,Oracle,Plsql,Triggers,我需要编写一个触发器，通过将旧值插入或更新到同一表中的另一行，在更新列之前保留该列的旧值。（是的，我知道）。下面的合并/双重欺骗对我很有用，但因为在这种情况下，我要插入或更新同一个表， Oracle在运行时抱怨。此外，出于某种原因，我发现编写编译时没有错误的代码异常困难两个问题：即使我可以保证触发器永远不会更新触发触发器的行，也有可能修改触发器所在的同一个表吗？或者我必须做一些类似的事情（例如）：将挂起的更改插入到另一个表中，以便第二个触发器可以将它们合并回原始表中？（此表是一个客户界面

我需要编写一个触发器，通过将旧值插入或更新到同一表中的另一行，在更新列之前保留该列的旧值。（是的，我知道）。下面的合并/双重欺骗对我很有用，但因为在这种情况下，我要插入或更新同一个表， Oracle在运行时抱怨。此外，出于某种原因，我发现编写编译时没有错误的代码异常困难

两个问题：

即使我可以保证触发器永远不会更新触发触发器的行，也有可能修改触发器所在的同一个表吗？或者我必须做一些类似的事情（例如）：将挂起的更改插入到另一个表中，以便第二个触发器可以将它们合并回原始表中？（此表是一个客户界面，因此我无法重新构建此表以使用第二个表永久存储旧值。）

不允许我在MERGE语句中使用：old.event\u key，但允许我在MERGE语句中使用：old.property\u val的编译器错误是怎么回事？（声明变量old\u event\u key并将其分配给：old.event\u key的值似乎有效）是否存在某种隐藏的中间语言，可以知道列何时（属于）主键，并阻止您通过：old引用它。

以下是违规代码：

create or replace trigger remember_old_status
  before update on event_properties
  for each row
    when (old.property_name = 'CURRENT-STATUS')
    declare
      old_event_key varchar2(20);
    begin
      old_event_key := :old.event_key;
      merge into event_properties eprop
        using (select 1 from dual) dummy
        on (    eprop.event_key = old_event_key
            AND eprop.property_name = 'PREVIOUS-STATUS')
        when matched then
          update set property_val = :old.property_val
        when not matched then
          insert (event_key, property_name, property_val)
          values (old_event_key, 'PREVIOUS-STATUS', :old.property_val);
    end;

这是表格：

CREATE TABLE "CUST"."EVENT_PROPERTIES" 
 (  "EVENT_KEY" VARCHAR2(20 BYTE) CONSTRAINT "NN_FLE_FLK" NOT NULL ENABLE, 
  "PROPERTY_NAME" VARCHAR2(20 BYTE) CONSTRAINT "NN_FLE_PN" NOT NULL ENABLE, 
  "PROPERTY_VAL" VARCHAR2(80 BYTE), 
   CONSTRAINT "PX_EVENT_PROPERTIES" PRIMARY KEY ("EVENT_KEY", "PROPERTY_NAME") DEFERRABLE
USING INDEX PCTFREE 10 INITRANS 2 MAXTRANS 255 COMPUTE STATISTICS 
STORAGE(INITIAL 65536 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645
PCTINCREASE 0 FREELISTS 1 FREELIST GROUPS 1
BUFFER_POOL DEFAULT FLASH_CACHE DEFAULT CELL_FLASH_CACHE DEFAULT)
TABLESPACE "CUST_TS"  ENABLE
 ) SEGMENT CREATION IMMEDIATE 
PCTFREE 10 PCTUSED 40 INITRANS 1 MAXTRANS 255 
NOCOMPRESS LOGGING
STORAGE(INITIAL 65536 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645
PCTINCREASE 0 FREELISTS 1 FREELIST GROUPS 1
BUFFER_POOL DEFAULT FLASH_CACHE DEFAULT CELL_FLASH_CACHE DEFAULT)
TABLESPACE "CUST_TS" ;

以下是错误消息：

ORA-04091:表CUST.EVENT_属性正在变化，触发器/函数可能看不到它 ORA-06512：在第5行的“客户记住旧的状态”

您可以使用将旧值存储在每一行部分之前的

变量中，然后在之后的语句
中合并
create or replace trigger remember_old_status
for update on event_properties
compound trigger

  type t_type is table of event_properties%rowtype;
  old_recs t_type := t_type();

  before each row is
  begin
    if (:old.property_name = 'CURRENT-STATUS') then
      old_recs.extend();
      old_recs(old_recs.count).event_key := :old.event_key;
      old_recs(old_recs.count).property_name := :old.property_name;
      old_recs(old_recs.count).property_val := :old.property_val;
    end if;
  end before each row;

  after statement is
  begin
    forall i in old_recs.first..old_recs.last
      merge into event_properties eprop
        using (
          select old_recs(i).event_key as event_key, 
            'PREVIOUS-STATUS' as property_name,
            old_recs(i).property_val as property_val
            from dual
        ) dummy
        on (eprop.event_key = dummy.event_key
            and eprop.property_name = dummy.property_name)
        when matched then
          update set property_val = old_recs(i).property_val
        when not matched then
          insert (event_key, property_name, property_val)
          values (dummy.event_key, dummy.property_name, dummy.property_val);
  end after statement;
end remember_old_status;
/

这假设您一次只更新一行：
create or replace trigger remember_old_status
for update on event_properties
compound trigger

  old_rec event_properties%rowtype;

  before each row is
  begin
    if (:old.property_name = 'CURRENT-STATUS') then
      old_rec.event_key := :old.event_key;
      old_rec.property_name := :old.property_name;
      old_rec.property_val := :old.property_val;
    end if;
  end before each row;

  after statement is
  begin
    if (old_rec.property_name = 'CURRENT-STATUS') then
      merge into event_properties eprop
        using (
          select old_rec.event_key as event_key, 
            'PREVIOUS-STATUS' as property_name,
            old_rec.property_val as property_val
            from dual
        ) dummy
        on (eprop.event_key = dummy.event_key
            and eprop.property_name = dummy.property_name)
        when matched then
          update set property_val = old_rec.property_val
        when not matched then
          insert (event_key, property_name, property_val)
          values (dummy.event_key, dummy.property_name, dummy.property_val);
    end if;
  end after statement;
end remember_old_status;
/

快速测试：
insert into event_properties values('SOME_EVENT', 'CURRENT-STATUS', 'A');

1 row inserted.

update event_properties set property_val = 'B' where event_key = 'SOME_EVENT' and property_name = 'CURRENT-STATUS';

1 row updated.

select * from event_properties;

EVENT_KEY            PROPERTY_NAME        PROPERTY_VAL                                                                    
-------------------- -------------------- --------------------------------------------------------------------------------
SOME_EVENT           CURRENT-STATUS       B                                                                               
SOME_EVENT           PREVIOUS-STATUS      A                                                                               

update event_properties set property_val = 'C' where event_key = 'SOME_EVENT' and property_name = 'CURRENT-STATUS';

1 row updated.

select * from event_properties;

EVENT_KEY            PROPERTY_NAME        PROPERTY_VAL                                                                    
-------------------- -------------------- --------------------------------------------------------------------------------
SOME_EVENT           CURRENT-STATUS       C                                                                               
SOME_EVENT           PREVIOUS-STATUS      B                                                                               

如果要处理一条语句中的多个更新，则每行之前的可以填充一个集合，然后可以在之后的语句中使用该集合
create or replace trigger remember_old_status
for update on event_properties
compound trigger

  type t_type is table of event_properties%rowtype;
  old_recs t_type := t_type();

  before each row is
  begin
    if (:old.property_name = 'CURRENT-STATUS') then
      old_recs.extend();
      old_recs(old_recs.count).event_key := :old.event_key;
      old_recs(old_recs.count).property_name := :old.property_name;
      old_recs(old_recs.count).property_val := :old.property_val;
    end if;
  end before each row;

  after statement is
  begin
    forall i in old_recs.first..old_recs.last
      merge into event_properties eprop
        using (
          select old_recs(i).event_key as event_key, 
            'PREVIOUS-STATUS' as property_name,
            old_recs(i).property_val as property_val
            from dual
        ) dummy
        on (eprop.event_key = dummy.event_key
            and eprop.property_name = dummy.property_name)
        when matched then
          update set property_val = old_recs(i).property_val
        when not matched then
          insert (event_key, property_name, property_val)
          values (dummy.event_key, dummy.property_name, dummy.property_val);
  end after statement;
end remember_old_status;
/

您可以使用将旧值存储在每一行
部分之前的变量中，然后在之后的语句
中合并
create or replace trigger remember_old_status
for update on event_properties
compound trigger

  type t_type is table of event_properties%rowtype;
  old_recs t_type := t_type();

  before each row is
  begin
    if (:old.property_name = 'CURRENT-STATUS') then
      old_recs.extend();
      old_recs(old_recs.count).event_key := :old.event_key;
      old_recs(old_recs.count).property_name := :old.property_name;
      old_recs(old_recs.count).property_val := :old.property_val;
    end if;
  end before each row;

  after statement is
  begin
    forall i in old_recs.first..old_recs.last
      merge into event_properties eprop
        using (
          select old_recs(i).event_key as event_key, 
            'PREVIOUS-STATUS' as property_name,
            old_recs(i).property_val as property_val
            from dual
        ) dummy
        on (eprop.event_key = dummy.event_key
            and eprop.property_name = dummy.property_name)
        when matched then
          update set property_val = old_recs(i).property_val
        when not matched then
          insert (event_key, property_name, property_val)
          values (dummy.event_key, dummy.property_name, dummy.property_val);
  end after statement;
end remember_old_status;
/

这假设您一次只更新一行：
create or replace trigger remember_old_status
for update on event_properties
compound trigger

  old_rec event_properties%rowtype;

  before each row is
  begin
    if (:old.property_name = 'CURRENT-STATUS') then
      old_rec.event_key := :old.event_key;
      old_rec.property_name := :old.property_name;
      old_rec.property_val := :old.property_val;
    end if;
  end before each row;

  after statement is
  begin
    if (old_rec.property_name = 'CURRENT-STATUS') then
      merge into event_properties eprop
        using (
          select old_rec.event_key as event_key, 
            'PREVIOUS-STATUS' as property_name,
            old_rec.property_val as property_val
            from dual
        ) dummy
        on (eprop.event_key = dummy.event_key
            and eprop.property_name = dummy.property_name)
        when matched then
          update set property_val = old_rec.property_val
        when not matched then
          insert (event_key, property_name, property_val)
          values (dummy.event_key, dummy.property_name, dummy.property_val);
    end if;
  end after statement;
end remember_old_status;
/

快速测试：
insert into event_properties values('SOME_EVENT', 'CURRENT-STATUS', 'A');

1 row inserted.

update event_properties set property_val = 'B' where event_key = 'SOME_EVENT' and property_name = 'CURRENT-STATUS';

1 row updated.

select * from event_properties;

EVENT_KEY            PROPERTY_NAME        PROPERTY_VAL                                                                    
-------------------- -------------------- --------------------------------------------------------------------------------
SOME_EVENT           CURRENT-STATUS       B                                                                               
SOME_EVENT           PREVIOUS-STATUS      A                                                                               

update event_properties set property_val = 'C' where event_key = 'SOME_EVENT' and property_name = 'CURRENT-STATUS';

1 row updated.

select * from event_properties;

EVENT_KEY            PROPERTY_NAME        PROPERTY_VAL                                                                    
-------------------- -------------------- --------------------------------------------------------------------------------
SOME_EVENT           CURRENT-STATUS       C                                                                               
SOME_EVENT           PREVIOUS-STATUS      B                                                                               

如果要处理一条语句中的多个更新，则每行之前的可以填充一个集合，然后可以在之后的语句中使用该集合
create or replace trigger remember_old_status
for update on event_properties
compound trigger

  type t_type is table of event_properties%rowtype;
  old_recs t_type := t_type();

  before each row is
  begin
    if (:old.property_name = 'CURRENT-STATUS') then
      old_recs.extend();
      old_recs(old_recs.count).event_key := :old.event_key;
      old_recs(old_recs.count).property_name := :old.property_name;
      old_recs(old_recs.count).property_val := :old.property_val;
    end if;
  end before each row;

  after statement is
  begin
    forall i in old_recs.first..old_recs.last
      merge into event_properties eprop
        using (
          select old_recs(i).event_key as event_key, 
            'PREVIOUS-STATUS' as property_name,
            old_recs(i).property_val as property_val
            from dual
        ) dummy
        on (eprop.event_key = dummy.event_key
            and eprop.property_name = dummy.property_name)
        when matched then
          update set property_val = old_recs(i).property_val
        when not matched then
          insert (event_key, property_name, property_val)
          values (dummy.event_key, dummy.property_name, dummy.property_val);
  end after statement;
end remember_old_status;
/

请看以下示例：。其中一个选项显示了如何使用“另一个表”（您提到的），这是一个全局临时表，而第二个选项演示了在包变量中使用集合。任何对Oracle文档的检查或在ORA-04091
上搜索此站点都会清楚地给出“否”的答案。不能对每行触发的表执行DML。解决这个问题的模式是对每一行使用更新另一个表。然后让一个after
语句级触发器使用另一个表中的信息来更新被触发的表。在问题的第二部分中，您指的是什么编译器错误？直接在代码中使用old.event\u键
可以编译OK。好吧，不管怎样，在一个问题中问两个问题是没有帮助的；如果您仍然可以重现实际代码和错误，那么您应该单独问一个问题。请看以下示例：。其中一个选项显示了如何使用“另一个表”（您提到的），这是一个全局临时表，而第二个选项演示了在包变量中使用集合。任何对Oracle文档的检查或在ORA-04091
上搜索此站点都会清楚地给出“否”的答案。不能对每行触发的表执行DML。解决这个问题的模式是对每一行使用更新另一个表。然后让一个after
语句级触发器使用另一个表中的信息来更新被触发的表。在问题的第二部分中，您指的是什么编译器错误？直接在代码中使用old.event\u键
可以编译OK。好吧，不管怎样，在一个问题中问两个问题是没有帮助的；如果您仍然可以重现代码和错误，那么您应该单独询问显示实际代码和错误的问题。