Oracle触发器表发生了变化 触发器不能读它解决方法详解数据库

出现原因，是因为在更新的的表和读取的表是同一个表。

  CREATE or replace TRIGGER T_userupdateT  BEFORE update  ON T_user  REFERENCING OLD AS old  NEW AS N_ROW   FOR EACH ROW  
DECLARE U_xtfidemp1 varchar(36); 
 u_xtempcode1 varchar(20); 
 u_xtempcodeCount int:=0;  
 U_xtfidempCount int:=0;  
 u_id1 int:=0;  
BEGIN  
  U_xtfidemp1:=:N_ROW.U_xtfidemp; 
  u_xtempcode1:=:N_ROW.u_xtempcode; 
  u_id1:=:N_ROW.u_id; 
  select count(u_xtempcode) into u_xtempcodeCount from eas.T_user where u_xtempcode is not null and u_xtempcode=u_xtempcode1 and u_id<>u_id1; 
  select count(U_xtfidemp) into U_xtfidempCount from eas.T_user where U_xtfidemp is not null and U_xtfidemp=U_xtfidemp1 and u_id<>u_id1;   
 IF u_xtempcodeCount>0 or U_xtfidempCount>0  THEN 
         RAISE_APPLICATION_ERROR(-20001, 'eas.T_user u_xtempcode,U_xtfidemp,U_GZCode更新数据时有错误,有重复'); 
 END IF; 
 end;

出现错误时，是因为触发器在T_userupdateT在T_user上，触发器内部有读取了T_user所以有错误。

修改如下

  CREATE or replace TRIGGER T_userupdateT  BEFORE update  ON T_user  REFERENCING OLD AS old  NEW AS N_ROW   FOR EACH ROW  
DECLARE U_xtfidemp1 varchar(36); 
 u_xtempcode1 varchar(20); 
 u_xtempcodeCount int:=0;  
 U_xtfidempCount int:=0;  
 u_id1 int:=0;  
PRAGMA AUTONOMOUS_TRANSACTION; 
BEGIN  
  U_xtfidemp1:=:N_ROW.U_xtfidemp; 
  u_xtempcode1:=:N_ROW.u_xtempcode; 
  u_id1:=:N_ROW.u_id; 
  select count(u_xtempcode) into u_xtempcodeCount from eas.T_user where u_xtempcode is not null and u_xtempcode=u_xtempcode1 and u_id<>u_id1; 
  select count(U_xtfidemp) into U_xtfidempCount from eas.T_user where U_xtfidemp is not null and U_xtfidemp=U_xtfidemp1 and u_id<>u_id1;   
 IF u_xtempcodeCount>0 or U_xtfidempCount>0  THEN 
         RAISE_APPLICATION_ERROR(-20001, 'eas.T_user u_xtempcode,U_xtfidemp,U_GZCode更新数据时有错误,有重复'); 
 END IF; 
COMMIT; 
 end;

多了PRAGMA AUTONOMOUS_TRANSACTION;COMMIT;两句