Update record set in same column with max id in it(2 Cursors update)

DECLARE 
CURSOR C1 IS
SELECT MAX(COLUMN_NAME1) AS HEADERID FROM TABLE_NAME WHERE CONDITIONS ;


CURSOR C2 IS
SELECT ID FROM TABLE_NAME WHERE CONDITIONS AND COLUMN_NAME1 IS NULL;

L_MAX_HEADERID number;
BEGIN 


OPEN C1;
FETCH C1 INTO L_MAX_HEADERID;
CLOSE C1;

FOR R1 IN C2

LOOP

L_MAX_HEADERID :=L_MAX_HEADERID+1;

UPDATE TABLE_NAME SET
       COLUMN_NAME1=L_MAX_HEADERID
       WHERE ID=R1.ID;
       
       
       
END LOOP;
END;