给DB数据表加强制索引

• DB2 数据库会根据DB层的统计值决定 根据查询条件走哪一个索引，某些情况下，由于未知原因，索引会走偏，故程序中可以规定程序走哪一个索引来避免索引走偏的情况发生。

 强制走索引的 实例代码如下：

SELECT vbeln
      zorgdn
      vstel
      zstaff
      zvtweg
      vsbed zacty
      zlifsk  erdat lfdat AS zdtday zebeln
   INTO CORRESPONDING FIELDS OF TABLE it_likp
   FROM likp
   WHERE    vbeln IN s_vbeln
   AND erdat IN s_erdat
   AND lfart = 'ZCRE'
   AND vstel IN r_vstel
   AND zebeln IN s_zebeln
   AND zorgdn = space
  AND lfdat IN s_zpldat
%_HINTS DB6 '<IXSCAN TABLE=''LIKP'' SAP_INDEX=''Z06'' />'. "#EC CI_HINTS

%_hints db6 '&SUBSTITUTE LITERALS&'.                      "#EC CI_HINTS

where    vbeln in s_vbeln
               and erdat in s_erdat
               and lfart = 'ZCRE'
               and vstel in r_vstel
               and zebeln in s_zebeln
               and zorgdn = space
              and lfdat in s_zpldat
* %_HINTS DB6 '&max_blocking_factor 5&' "#EC CI_HINTS
%_hints db6 '&SUBSTITUTE LITERALS&'.