Oracle触发器表发生了变化 触发器不能读它的解决方法(必看)

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