Oracle表数据导入xml

create or replace directory exp_dir as 'e:\oracle';
/

create or replace procedure table2xml(result   in out nocopy clob,
                                         filename in varchar2) is
  xmlstr  varchar2(32767);
  line    varchar2(2000);
  fhandle utl_file.file_type;
begin
  fhandle := utl_file.fopen('EXP_DIR', filename, 'w');
  xmlstr  := dbms_lob.substr(result, 32767);
  loop
    exit when xmlstr is null;
    line := substr(xmlstr, 1, instr(xmlstr, chr(10)) - 1);
    dbms_output.put_line('| ' || line);
    utl_file.put_line(fhandle, line);
    xmlstr := substr(xmlstr, instr(xmlstr, chr(10)) + 1);
  end loop;
  utl_file.fclose(fhandle);
end;
/

declare
  queryctx dbms_xmlquery.ctxType;
  result   clob;
begin
  queryctx := dbms_xmlquery.newContext('select username from all_users where username<>''SYSTEM'' and username<>''SCOTT''');
  result   := dbms_xmlquery.getXML(queryctx);
  table2xml(result, 'table2xml.xml');
  dbms_xmlquery.closeContext(queryctx);
end;