查询某个原物料下的子组件：
select level,
t.*
from (select items1.segment1 segment1_m,
items1.inventory_item_id m_id,
items1.description description_m,
materials.bill_sequence_id,
components.item_num,
components.operation_seq_num,
components.component_item_id sub_id,
items2.segment1 segment1_sub,
items2.description description_sub,
components.component_quantity,
components.EFFECTIVITY_DATE,
components.DISABLE_DATE
from bom_bill_of_materials materials,
mtl_system_items_b items1,
bom_inventory_components components,
mtl_system_items_b items2
where materials.assembly_item_id = items1.inventory_item_id
and materials.bill_sequence_id = components.bill_sequence_id
and components.component_item_id = items2.inventory_item_id
and items2.organization_id = 103
and materials.organization_id = 103
and items1.organization_id = 103
and components.EFFECTIVITY_DATE <= sysdate
and nvl(components.DISABLE_DATE,sysdate+1) > sysdate
) t
connect by prior t.segment1_sub = t.segment1_m
start with t.segment1_m = 'S-7BR1AUX-B1';
--connect by prior t.sub_id = t.m_id
-- start with t.m_id = '19044'