I am having PLS-00103: Encountered the symbol - oracle

Question

i am having
PLS-00103: Encountered the symbol "END" when expecting one of the
following: ( begin case declare exit for goto if loop mod null
pragma raise return select update while with << continue
close current delete fetch lock insert open rollback savepoint set
sql execute commit forall merge pipe purge error
and i have searched everywhere but couldnt find how to solve
CREATE TABLE UPAYMENT AS SELECT * FROM PAYMENT ;
DROP TRIGGER A;
CREATE OR REPLACE TRIGGER A
after insert ON Upayment
FOR EACH ROW
DECLARE
ERROR_ EXCEPTION ;
h varchar2(20);
NOFOUND EXCEPTION ;
CURSOR Y3 IS
SELECT PAYMENT_DATE FROM UPAYMENT ;
BEGIN
OPEN Y3;
loop fetch Y3 into h;
IF Y3%NOTFOUND THEN RAISE NOTFOUND;
IF (:NEW.PAYMENT_DATE >= '01-JAN-22'and INSERTING)
THEN
:NEW.AMOUNT := :NEW.AMOUNT * 1.5;
ELSE
END LOOP;
END IF;
CLOSE Y3;
END IF;
exception when ERROR_
then DBMS_OUTPUT.PUT_LINE('ERROR');
END;

Answer 1

Quite a few errors.
trigger fires on insert; you don't have to check whether you're inserting (besides, you can't do that as you did)
don't compare dates to strings; use date literal or TO_DATE function with appropriate format mask
you can't modify :new values in an after trigger; must be before
you can't (actually, you shouldn't) end loop in the middle of IF
what do you need the loop for, anyway?
When fixed, trigger looks like this and kind of works:
SQL> create or replace trigger a
2 before insert on upayment
3 for each row
4 declare
5 error_ exception ;
6 h varchar2(20);
7 nofound exception ;
8 cursor y3 is
9 select payment_date from upayment ;
10 begin
11 open y3;
12 loop
13 fetch y3 into h;
14
15 if y3%notfound then
16 raise nofound;
17 else
18 if :new.payment_date >= date '2022-01-01' then
19 :new.amount := :new.amount * 1.5;
20 end if;
21 end if;
22 end loop;
23 close y3;
24
25 exception when nofound then
26 dbms_output.put_line('ERROR');
27 end;
28 /
Trigger created.
SQL> desc upayment
Name Null? Type
----------------------------------------- -------- ----------------------------
PAYMENT_DATE DATE
AMOUNT NUMBER
SQL> insert into upayment (payment_date, amount) values (sysdate, 100);
ERROR
1 row created.
SQL>
Though, I guess that you could simplify it (remove cursor, loop, user-defined exception, ... what not) to
SQL> create or replace trigger a
2 before insert on upayment
3 for each row
4 begin
5 if :new.payment_date >= date '2022-01-01' then
6 :new.amount := :new.amount * 1.5;
7 end if;
8 end;
9 /
Trigger created.
SQL> insert into upayment (payment_date, amount) values (sysdate, 500);
1 row created.
SQL> select * from upayment;
PAYMENT_DATE AMOUNT
------------------- ----------
19.01.2022 22:28:03 150
19.01.2022 22:32:57 750
SQL>