MRP运算逻辑

[tr] [td=72]BOM： [td=47] [td=116] [td=57] [td=72] [td=72] [td=72] [td=72]
[tr] [td]父项 [td]用量 [td]子项 [td]用量 [td]替代件 [td]用量 [td] [td]
[tr] [td]产品A [td]1 [td]晶片A [td]1 [td]晶片B [td]1 [td] [td]
[tr] [td]产品B [td]1 [td]晶片B [td]1 [td]晶片A [td]1 [td] [td]
[tr] [td] [td] [td] [td] [td] [td] [td] [td]
[tr] [td]需求： [td] [td] [td] [td] [td] [td] [td]
[tr] [td]产品 [td]数量 [td]需求日期 [td] [td] [td] [td] [td]
[tr] [td]产品A [td]200 [td]2015/11/29 [td] [td] [td] [td] [td]
[tr] [td]产品B [td]300 [td]2015/12/22 [td] [td] [td] [td] [td]
[tr] [td] [td] [td] [td] [td] [td] [td] [td]
[tr] [td]供应： [td] [td] [td] [td] [td] [td] [td]
[tr] [td]材料 [td]数量 [td]供应日期 [td] [td] [td] [td] [td]
[tr] [td]晶片A [td]300 [td]2015/11/5 [td] [td] [td] [td] [td]
[tr] [td]晶片B [td]100 [td]2015/10/29 [td] [td] [td] [td] [td]
[tr] [td] [td] [td] [td] [td] [td] [td] [td]
[tr] [td=3,1]运算结果:（需采购） [td] [td] [td] [td] [td]
[tr] [td]晶片A [td]100 [td]2015/11/29 [td] [td] [td] [td] [td]
[tr] [td] [td] [td] [td] [td] [td] [td] [td]
[tr] [td=3,1]为什么运算后的结果不是 [td] [td] [td] [td] [td]
[tr] [td]晶片B [td]100 [td]2015/12/22 [td] [td] [td] [td] [td]
[tr] [td] [td] [td] [td] [td] [td] [td] [td]
[tr] [td=8,1]这种“循环替代”的过程，运算的逻辑是怎样的，先满足需求日期后的，往回算？（上面例子无提前期）
[tr] [td] [td] [td] [td] [td] [td] [td] [td]
[tr] [td=2,1]版本：5.0 [td] [td] [td] [td] [td] [td]
[tr] [td=3,1]补丁：2015-09-10 [td] [td] [td] [td] [td]
[tr] [td=3,1]联系人：方主仕 QQ:285544628 [td] [td] [td] [td] [td]