Oracle 檢測clog欄位錯誤的SQL

Codedeclare  pag    number;  len    number;  c      varchar2(10);  charpp number := 8132/2;begin  for r in (select rowid rid,log_id, dbms_lob.getlength (CONTENT) len            from  temp_data_collect_log ) loop    if r.len is not null then      for page in 0..r.len/charpp  loop        begin          select dbms_lob.substr (CONTENT, 1, 1+ (page * charpp))          into   c          from   temp_data_collect_log           where  rowid = r.rid;                exception          when others then            dbms_output.put_line ('Error on log_id' ||R.log_id||' page '||page);            dbms_output.put_line (sqlerrm);        end;      end loop;    end if;  end loop;end;