oracle for update和for update nowait的区别

   SELECT h.data_source, h.display_po_number, h.type_lookup_code
      INTO v_data_source, v_display_po_number, v_type_lookup_code
      FROM pur_headers_all h, pur_lines_all l
     WHERE h.pur_header_id = l.pur_header_id
       AND l.pur_line_id = p_pur_line_id
       FOR UPDATE NOWAIT;

 

来源：https://www.cnblogs.com/quanweiru/archive/2012/11/09/2762223.html