Convert CLOB to BLOB

declare
  l_blob        blob;
  l_amt         integer := dbms_lob.lobmaxsize;
  l_dest_offset integer := 1;
  l_src_offset  integer := 1;
  l_csid        integer := dbms_lob.default_csid;
  l_ctx         integer := dbms_lob.default_lang_ctx;
  l_warn        integer;
begin
    DBMS_LOB.CREATETEMPORARY(l_blob, TRUE);
    for rrr in (select stage_data from HR.CLOB_STAGE)
        loop
        DBMS_LOB.convertToBlob(l_blob,
                           rrr.stage_data,
                           l_amt,
                           l_dest_offset,
                           l_src_offset,
                           l_csid,
                           l_ctx,
                           l_warn );
            insert into HR.BLOB_STAGE (stage_data) values (l_blob);
        end loop;
        commit;
end;
/