Pfthb

I need to create a procedure which generates a excel sheet including query output.
Please help!

Check out Rene Nyffenegger solution github: https://github.com/ReneNyffenegger/xlsx_writer-Oracle

As far as I'm aware there is no Oracle supplied package that generates xsl/xslx files

You may create such a package (Formerly we derived from Tom Kyte) :

create or replace package to_excel is
 procedure xls(my_query in varchar2);
 procedure xls(my_query in varchar2,p_tip in varchar2);
 procedure xls2(my_query in varchar2); 
 procedure csv(my_query in varchar2,p_tip in varchar2);
end;

create or replace package body to_excel is
procedure xls(my_query in varchar2) is
begin
 owa_util.mime_header( ccontent_type => 'application/excel');
 --, ccharset => 'WE8ISO8859P9' ); -- , ccharset => 'TR8MSWIN1254' , 'UTF-8' 
 owa_sylk.show( p_query=>replace(my_query,'x*x','%') );
end;

procedure xls(my_query in varchar2,p_tip in varchar2) is
begin
 owa_util.mime_header( 'application/excel' );
 owa_sylk.show( p_query=>replace(my_query,'x*x','%'), p_tip=>p_tip );
end;

procedure xls2(my_query in varchar2) is
begin
 owa_util.mime_header('application/vnd.ms-excel',false);
 htp.p('Cache-Control: no-store');
 htp.p('Expires: -1');
 owa_util.http_header_close;
 owa_sylk.show( p_query=>replace(my_query,'x*x','%') );

end;
procedure csv(my_query in varchar2,p_tip in varchar2) is
begin
 owa_util.mime_header( 'application/csv' );
 owa_sylk.show( p_query=>replace(my_query,'x*x','%'), p_tip=>p_tip );
end;


end;

that's a nice, useful method directly called from web browser such as https://..../pls/<dad_name>/<schema_name>.to_excel.xls?my_query=select sysdate from dual