Created by Jerry Wang, last modified on Mar 21, 2014
通过这个wiki,我们很容易能得到一个business object instance，例如product，下面包含的attachment 信息。
那么反过来， 已知一个attachment的physical instance guid，也能找到这个attachment是属于哪个product instance的。
例如我们已知一个physical instance的guid 为FA163E5CA86F1ED3A888F18542E37D7B， 可以通过下面的代码找到是哪一个product 包含了该attachment：
DATA: ls_ph TYPE bdsphio22,
ls_product TYPE comm_product,
lv_instance_b TYPE skwg_brel-instid_b,
ls_relation TYPE skwg_brel.
“因为任何一个physical instance一定对应一个logical instance(多对一的关系)，所以可以用select single的方式找到对应的logical instance guid:
SELECT SINGLE * INTO ls_ph FROM bdsphio22 WHERE phio_id = 'FA163E5CA86F1ED3A888F18542E37D7B'.
CHECK sy-subrc = 0.
" relationship表里的naming convention：</>
lv_instance_b = 'L/' && ls_ph-lo_class && '/' && ls_ph-loio_id.
" business object和其attachment 的对应关系统一维护在SKWG_BREL这张表里
SELECT SINGLE * INTO ls_relation FROM skwg_brel WHERE instid_b = lv_instance_b AND typeid_a = 'BUS1178'.
CHECK sy-subrc = 0.
" product的guid就包含在ls_relation-instid_a里
SELECT SINGLE * INTO ls_product FROM comm_product WHERE product_guid = ls_relation-instid_a.
CHECK sy-subrc = 0.
"最终输出product ID
WRITE: / ls_product-product_id.
测试结果和UI上观察到的attachment一致：
也可以直接使用function module CRM_KW_DOCUMENT_ROOTS_GET