Referred from Oracle APEX Page Designer Help .

How to upload Multiple files in APEX?

declare
    l_file_names apex_t_varchar2;
    l_file       apex_application_temp_files%rowtype;
begin
    l_file_names := apex_string.split (
                        p_str => :page item name,
                        p_sep => ':' );
    for i in 1 .. l_file_names.count loop
        select *
          into l_file
          from apex_application_temp_files
         where name = l_file_names(i);
        -- add code here to store the uploaded file in your own table
    end loop;
end;