Dynamic SQL - Execute Immediate & Bulk Collection

DECLARE
  TYPE emp_ref_cursor IS REF CURSOR;
  TYPE empno_tab IS TABLE OF NUMBER;
  TYPE ename_tab IS TABLE OF VARCHAR2(50);
 
  v_emp_cur  emp_ref_cursor;
  vc_empno   empno_tab;
  vc_sal     empno_tab;
  vc_ename   ename_tab;
  vc_ename1  ename_tab;
  vc_ename2  ename_tab;
  v_sql_stmt VARCHAR2(500);
  v_bonus    CONSTANT NUMBER := 500;
  a_null CHAR(1);
BEGIN
  -- example of ref cursor with bulk collect
  v_sql_stmt := 'SELECT empno, ename FROM emp_t WHERE deptno = 10';
  OPEN v_emp_cur FOR v_sql_stmt;
  FETCH v_emp_cur BULK COLLECT INTO vc_empno,vc_ename;
  CLOSE v_emp_cur;
 
  -- example of dynamic sql with bull collect
  v_sql_stmt := 'SELECT sal FROM emp_t';
  EXECUTE IMMEDIATE v_sql_stmt BULK COLLECT INTO vc_sal;
 
  -- example of dynamic sql with returning bulk collect
  v_sql_stmt := 'UPDATE emp_t SET sal = sal + :1
                 RETURNING ename INTO :2';
  EXECUTE IMMEDIATE v_sql_stmt
              USING v_bonus RETURNING BULK COLLECT INTO vc_ename1;
 
  --dynamic sql inside forall statement
  v_sql_stmt := 'UPDATE emp_t SET sal = sal - :1
                WHERE empno = :2 RETURNING ENAME INTO :3';
  FORALL i in vc_empno.first..vc_empno.last
     EXECUTE IMMEDIATE v_sql_stmt USING v_bonus, vc_empno(i)
                      RETURNING BULK COLLECT INTO vc_ename2;
    
  FOR i in vc_ename2.first..vc_ename2.last LOOP
     dbms_output.put_line(vc_ename2(i));
  END LOOP;
 
  -- passing null to dynamic sql
  EXECUTE IMMEDIATE 'UPDATE emp_t SET comm = :1' USING a_null;
  ROLLBACK;
 
EXCEPTION
 WHEN OTHERS THEN
  dbms_output.put_line('When others exception raised '|| sqlerrm);
END;