SQL & PL/SQL

Dear Experts,

                           copy a row and insert new row  on same table when column cardnumber_hashed matches in both TEMP_BACK and MAIN_table.

CREATE TABLE TEMP_BACK

(

CARDNUMBER_HASHED VARCHAR2(30),

NEWCARDNUMBER_HASHED VARCHAR2(30),

OPERATION VARCHAR2(30)

);

Insert into TEMP_BACK (CARDNUMBER_HASHED,NEWCARDNUMBER_HASHED,OPERATION) values ('f36nha3s7JfdRcmwR+f2QuA3o7c=','JQwvV8bmSgoFzj1Q3XU9qj9u1yw=','COPY');

CREATE TABLE MAIN_table

(

CARDHOLDER_NAME VARCHAR2(30),

CARDNUMBER_HASHED VARCHAR2(30) primary key,

BIN_ID VARCHAR2(30),

OPERATION VARCHAR2(30),

EMAIL_ADDRESS VARCHAR2(30)

);

Insert into MAIN_table (CARDHOLDER_NAME,CARDNUMBER_HASHED,BIN_ID,OPERATION,EMAIL_ADDRESS) values('JOHN','f36nha3s7JfdRcmwR+f2QuA3o7c=',201604843440554,'COPY','JOHN@GMAIL.COM');

Here i tried

-------------------------

  declare

  begin

  V_copy_DATA number;

  SELECT COUNT(1)

    INTO V_copy_DATA

    FROM TEMP_BACK a

    WHERE a.OPERATION='COPY'

AND EXISTS

      (SELECT 1 FROM MAIN_table b WHERE b.CARDNUMBER_HASHED = a.CARDNUMBER_HASHED;

if V_copy_DATA>0 then

INSERT

      INTO MAIN_table

        (

         CARDHOLDER_NAME,

          CARDNUMBER_HASHED

        )

      SELECT CARDHOLDER_NAME,

            NEWCARDNUMBER_HASHED

      FROM TEMP_BACK T2

      WHERE T2.OPERATION='COPY' 

AND t2.CARDNUMBER_HASHED in

(SELECT CARDNUMBER_HASHED from MAIN_table);

commit;

end if;

end;

     Desired output

Here i want cardnumber_hashed should be replaced as NEWCARDNUMBER_HASHED from TEMP_BACK table and insert rest of the data should remain as it is.