ORA 触发器的有关问题,大侠请进

DROP TABLE SIMM_H_F_MASTER CASCADE CONSTRAINTS ; CREATE TABLE SIMM_H_F_MASTER (   IMSI_H        VARCHAR2 (20)  NOT NULL,   MSISDN_H      VARCHAR2 (20)  NOT NULL,   NETWORKID     NUMBER (2)    NOT NULL,   PROVINCE_NUM  NUMBER (2),   IMSI_F        VARCHAR2 (20),   MSISDN_F      VARCHAR2 (20),   COS           VARCHAR2 (3),   STATUS        NUMBER (1)    DEFAULT 1 NOT NULL,   CONSTRAINT SIMM_H_F_MASTER_PK PRIMARY KEY ( MSISDN_H, NETWORKID ) USING INDEX ) ; DROP TABLE SIMM_UPDATE_SUBS_INFO CASCADE CONSTRAINTS ; CREATE TABLE SIMM_UPDATE_SUBS_INFO(  IMSI_H        VARCHAR2 (20)  NOT NULL,  MSISDN_H      VARCHAR2 (20)  NOT NULL,  IMSI_F        VARCHAR2 (20),  MSISDN_F      VARCHAR2 (20),  STATUS        NUMBER (1)      DEFAULT 1 NOT NULL,  SENDOUT       NUMBER (1)      DEFAULT 0 NOT NULL,  INSTANCE_NAME VARCHAR2 (20),   LAST_MODIFIED_DAT DATE ,  CONSTRAINT SIMM_UPDATE_SUBS_INFO PRIMARY KEY (IMSI_H) USING INDEX ) ;CREATE OR REPLACE TRIGGER TRIG_UPDATE_SUNBS　　    AFTER INSERT OR UPDATE OR DELETE ON SIMM_H_F_MASTER FOR EACH ROWBEGIN    if inserting then        if exists(SELECT IMSI_H FROM SIMM_UPDATE_SUBS_INFO WHERE  IMSI_H = :NEW.IMSI_H) then          delete  from SIMM_UPDATE_SUBS_INFO where  IMSI_H = :NEW.IMSI_H;        end if;        insert into SIMM_UPDATE_SUBS_INFO            (IMSI_H,MSISDN_H,IMSI_F,MSISDN_F,STATUS,LAST_MODIFIED_DAT,INSTANCE_NAME,SENDOUT) values (:NEW.IMSI_H,:NEW.MSISDN_H,:NEW.IMSI_F,:NEW.MSISDN_F,:NEW.STATUS,sysdate,'SIMM-R-CUINCOM',0);    end if;    if deleting then        update SIMM_UPDATE_SUBS_INFO set MSISDN_H=:OLD.MSISDN_H,IMSI_F=:OLD.IMSI_F,MSISDN_F=:OLD.MSISDN_F,STATUS=-1,LAST_MODIFIED_DAT=sysdate,SENDOUT=0 where IMSI_H=:OLD.IMSI_H;    end if;  if updating then        update SIMM_UPDATE_SUBS_INFO set MSISDN_H=:NEW.MSISDN_H,IMSI_F=:NEW.IMSI_F,MSISDN_F=:NEW.MSISDN_F,STATUS=:NEW.STATUS,LAST_MODIFIED_DAT=sysdate,SENDOUT=0 where IMSI_H=:OLD.IMSI_H;  end if;  END