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：

 1 SELECT vbeln
 2       zorgdn
 3       vstel
 4       zstaff
 5       zvtweg
 6       vsbed zacty
 7       zlifsk  erdat lfdat AS zdtday zebeln
 8    INTO CORRESPONDING FIELDS OF TABLE it_likp
 9    FROM likp
10    WHERE    vbeln IN s_vbeln
11    AND erdat IN s_erdat
12    AND lfart = 'ZCRE'
13    AND vstel IN r_vstel
14    AND zebeln IN s_zebeln
15    AND zorgdn = space
16   AND lfdat IN s_zpldat
17 %_HINTS DB6 '<IXSCAN TABLE=''LIKP'' SAP_INDEX=''Z06'' />'. "#EC CI_HINTS
18 
19 %_hints db6 '&SUBSTITUTE LITERALS&'.                      "#EC CI_HINTS
20 
21 where    vbeln in s_vbeln
22                and erdat in s_erdat
23                and lfart = 'ZCRE'
24                and vstel in r_vstel
25                and zebeln in s_zebeln
26                and zorgdn = space
27               and lfdat in s_zpldat
28 * %_HINTS DB6 '&max_blocking_factor 5&' "#EC CI_HINTS
29 %_hints db6 '&SUBSTITUTE LITERALS&'.