Problems encountered by Oracle using insert trigger and solutions

create or replace trigger 'trigger_name'--Trigger name
before insert --or after insert （Trigger timing）
--KeywordsbeforeandafterUsed to identify the trigger time，As the name implies，beforeThe command in the trigger isDMLExecute before modifying data，
--afterThe command in the trigger isDMLAfter modifying the data, execute it。
REFERENCING new as new --orold as old （Used for parameter usage in triggers）
--Note：beforeIn-housenewRefers to the currently inserted set，afterIn-houseoldRefers to the currently inserted set
FOR EACH ROW --Refers to the current trigger as a row-level trigger（Row-level trigger relative to statement-level trigger）
--Row-level triggers can pass :new.property and :old.property等获得updateor者insert发生之前的新值and发生值之后的旧值。
declare --Declare variables……
BEGIN
END;

TRIGGER TONGBUJIAYI_SFZH
before
 DELETE OR UPDATE of D_SFZH
 ON T_DA_JKDA_RKXZL
REFERENCING NEW AS NEW OLD AS OLD
 FOR EACH ROW
BEGIN
 IF UPDATING
 THEN
insert into T_DA_JKDA_RKXZL_GWANDJY(ID,D_GRDABH,P_RGID,D_SFZH,D_SFZHXGQ,D_DATZXGH,D_XM,D_BGSJ,D_BGZT)
VALUES (SYS_GUID(),:OLD.D_GRDABH,:OLD.P_RGID,:OLD.D_SFZH,:NEW.D_SFZH,'',:OLD.D_XM,sysdate,'2');
ELSIF DELETING
 THEN
insert into T_DA_JKDA_RKXZL_GWANDJY(ID,D_GRDABH,P_RGID,D_SFZH,D_SFZHXGQ,D_DATZXGH,D_XM,D_BGSJ,D_BGZT)
VALUES (SYS_GUID(),:OLD.D_GRDABH,:OLD.P_RGID,:OLD.D_SFZH,'','',:OLD.D_XM,sysdate,'1');
END IF;
END;

TRIGGER DETECTION_USERS_SYN_VACCINE
  BEFORE INSERT ON DETECTION_USERS
  REFERENCING new as new
  FOR EACH ROW

DECLARE --oracleOnly use once when declaring multiple attributesDECLAREJust
  V_ID              DETECTION_USERS.ID%TYPE;--The properties declared here are as followsDETECTION_USERSProperty declaration in table
  V_IS_VACCINATION  DETECTION_USERS.IS_VACCINATION%TYPE;
  V_VACCINE1        DETECTION_USERS.VACCINE1%TYPE;
  V_VACCINE2        DETECTION_USERS.VACCINE2%TYPE;
  V_VACCINE3        DETECTION_USERS.VACCINE3%TYPE;
  V_NUM_VACCINATION DETECTION_USERS.NUM_VACCINATION%TYPE;
  --Declare cursor query this person's previous vaccination information
  CURSOR latests is
    SELECT ID,
           IS_VACCINATION,
           VACCINE1,
           VACCINE2,
           VACCINE3,
           NUM_VACCINATION
      FROM (SELECT t.*, row_number() over(order by nvl(zdrq, '0') DESC) rn
              from (SELECT *
                      FROM (SELECT ID,
                                   IS_VACCINATION,
                                   VACCINE1,
                                   VACCINE2,
                                   VACCINE3,
                                   NUM_VACCINATION,
                                   (CASE
                                     WHEN (VACCINE3 IS NOT null) THEN
                                      VACCINE3
                                     WHEN (VACCINE2 IS NOT null) THEN
                                      VACCINE2
                                     WHEN (VACCINE1 IS NOT null) THEN
                                      VACCINE1
                                     ELSE
                                      ''
                                   END) AS zdrq
                              FROM DETECTION_USERS
                             WHERE "IDENTITY" = :new."IDENTITY"
                               AND IS_VACCINATION IS NOT NULL)) t)
     WHERE rn = 1;
BEGIN

  OPEN latests;
  FETCH latests
    INTO V_ID,
         V_IS_VACCINATION,
         V_VACCINE1,
         V_VACCINE2,
         V_VACCINE3,
         V_NUM_VACCINATION;
         ---Print statement
--  DBMS_OUTPUT.PUT_LINE('latests===' || V_ID || '**' || V_IS_VACCINATION || '**' ||
--                       V_VACCINE1 || '**' || V_VACCINE2 || '**' ||
--                       V_VACCINE3 || '**' || V_NUM_VACCINATION);
--  DBMS_OUTPUT.PUT_LINE('new===' || : || '**' || :new.IS_VACCINATION || '**' ||
--                       :new.VACCINE1 || '**' || :new.VACCINE2 || '**' ||
--                       :new.VACCINE3 || '**' || :new.NUM_VACCINATION);

  IF INSERTING THEN
    :new.IS_VACCINATION  := V_IS_VACCINATION;--Will be openedcursorAssign value to the newly inserted value
    :new.VACCINE1        := V_VACCINE1;
    :new.VACCINE2        := V_VACCINE2;
    :new.VACCINE3        := V_VACCINE3;
    :new.NUM_VACCINATION := V_NUM_VACCINATION;
  
  END IF;
  --FETCH NEXT FROM from_inserted INTOV_ID,V_IS_VACCINATION,V_VACCINE1,V_VACCINE2, V_VACCINE3,V_NUM_VACCINATION;
  --cycle，HerecursorOnly one，unnecessary。
  CLOSE latests;

END;