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&'.

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给DB数据表加强制索引

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