Oracle更新触发器问题

Question

问题是我有以下触发器来观察我的特定列“已更改”，如果它已更新为1我希望它将同一行和“CHANGED_DATE”列更新为当前的SYSDATE。由于某种原因，我一直得到这个错误任何帮助将不胜感激。

错误

UPDATE "SYSADM"."SHIP_CALENDAR" SET CHANGED = '1' WHERE ROWID = 'AABCxCAAEAAAKYEAAB' AND ORA_ROWSCN = '6165377066'
ORA-04091: table SYSADM.SHIP_CALENDAR is mutating, trigger/function may not see it
ORA-06512: at "SYSADM.SHIP_CALENDAR_CHANGED", line 5
ORA-04088: error during execution of trigger 'SYSADM.SHIP_CALENDAR_CHANGED'

触发

create or replace TRIGGER SHIP_CALENDAR_CHANGED
AFTER UPDATE
   OF CHANGED
   ON SHIP_CALENDAR
   REFERENCING OLD AS o NEW AS n
   FOR EACH ROW
DECLARE  
  BEGIN
     -- UPDATE SHIP CALENDAR SET UPDATE_CHANGE TO SYSDATE IF CHANGED CHANGES
     IF :n.CHANGED = '1' then  
       UPDATE SHIP_CALENDAR
         SET CHANGED_DATE = SYSDATE
         WHERE SHIPMENT_ID = :o.SHIPMENT_ID;
     END IF;  
END;

表

Answer 1

使用before update触发器：

create or replace TRIGGER SHIP_CALENDAR_CHANGED
BEFORE UPDATE
   OF CHANGED
   ON SHIP_CALENDAR
   REFERENCING OLD AS o NEW AS n
   FOR EACH ROW
DECLARE  
  BEGIN
     -- UPDATE SHIP CALENDAR SET UPDATE_CHANGE TO SYSDATE IF CHANGED CHANGES
     IF :n.CHANGED = '1' then  
        :n.CHANGED_DATE := SYSDATE
     END IF;  
END;