You can find custom CSV download steps below. (Without submit)
The button to download.
Ajax Callback process in the page.
begin htp.p('Content-type: text/csv'); htp.p('Content-disposition: attachment;filename=ledger.csv'); owa_util.http_header_close; htp.p('"Emp No","Emp Name"'); for i in ( select empno, ename from emp) loop htp.p('"'||i.empno||'","'||i.ename||'"'); end loop; end;