ABAP FOR ALL ENTRIES SELECT statement addition in SAP data retrieval

REPORT  ZSELECTCOMMAND.
*Select FOR ALL ENTRIES command
data: it_ekko type STANDARD TABLE OF ekko,
      wa_ekko like line of it_ekko,
      it_ekpo type standard table of ekpo,
      wa_ekpo like line of it_ekpo.
SELECT *
  UP TO 10 ROWS  "only return first 10 hits
  FROM ekko
  INTO TABLE it_ekko.
loop at it_ekko into wa_ekko.
  write:/ wa_ekko-ebeln.
endloop.
IF sy-subrc EQ 0.
* The FOR ALL ENTRIES comand only retrieves data which matches
* entries within a particular internal table.
  SELECT *
    FROM ekpo
    INTO TABLE it_ekpo
    FOR ALL ENTRIES IN it_ekko
    WHERE ebeln EQ it_ekko-ebeln.
  write:/ 'FOR ALL ENTRIES comand '.
  loop at it_ekpo into wa_ekpo.
    write:/ wa_ekpo-ebeln, wa_ekpo-ebelp.
  endloop.
ENDIF.

*Empty for all entries table
DATA: gd_lines TYPE i.
SELECT *
   FROM ekpo
   INTO TABLE it_ekpo
   WHERE ebeln EQ wa_ekko-ebeln.
DESCRIBE TABLE  it_ekpo LINES gd_lines.
WRITE:/ 'Number of lines without for all entries:', gd_lines.
*Restricts based on entries in it_ekko and ebeln EQ wa_ekko-ebeln
SELECT *
  FROM ekpo
  INTO TABLE it_ekpo
  FOR ALL ENTRIES IN it_ekko
  WHERE ebeln EQ it_ekko-ebeln
    AND ebeln EQ wa_ekko-ebeln.
DESCRIBE TABLE  it_ekpo LINES gd_lines.
WRITE:/ 'Number of lines with for all entries itab:', gd_lines.
*Only difference to the above code is that it_ekko is empty
REFRESH it_ekko.
SELECT *
 FROM ekpo
 INTO TABLE it_ekpo
 FOR ALL ENTRIES IN it_ekko
 WHERE ebeln EQ it_ekko-ebeln
   AND ebeln EQ wa_ekko-ebeln.
DESCRIBE TABLE  it_ekpo LINES gd_lines.
WRITE:/ 'Number of lines with empty for all entries itab:', gd_lines.