在Oracle 11 R2的可能有common table expression
:
测试数据:
-- drop table assembly;
create table assembly (
part_id number,
parent_part_id number,
quantity number
);
insert into assembly values (2, 1, 2);
insert into assembly values (3, 2, 10);
insert into assembly values (4, 1, 2);
insert into assembly values (5, 4, 1);
insert into assembly values (3, 5, 5);
select语句:
select
part_id,
sum(quantity_used) as quantity
from (
with assembly_hier (lvl, part_id, quantity, quantity_used) as (
select
1 lvl,
part_id,
quantity ,
quantity quantity_used
from
assembly
where
parent_part_id = 1
union all
select
assembly_hier.lvl + 1 lvl,
assembly .part_id,
assembly .quantity,
assembly_hier.quantity_used * assembly.quantity quantity_used
from
assembly_hier, assembly
where
assembly_hier.part_id = assembly.parent_part_id
)
select * from assembly_hier
)
group by part_id
order by part_id;
编辑此前Ora11R2,它可能工作与一个model clause
:
select
part_id,
sum(quantity) quantity
from (
select
lvl
parent_part_id,
part_id,
quantity
from (
select
lvl,
parent_part_id,
part_id,
quantity
from (
select
rownum r,
level lvl,
parent_part_id,
part_id,
quantity
from
assembly
start with parent_part_id = 1
connect by parent_part_id = prior part_id
)
)
model
dimension by (lvl, part_id)
measures (quantity, parent_part_id)
rules upsert (
quantity[ any, any ] order by lvl, part_id = quantity[cv(lvl) , cv(part_id)] *
nvl(quantity[cv(lvl)-1, parent_part_id[cv(lvl), cv(part_id)] ], 1)
)
)
group by part_id
order by part_id;
编辑II另一种可能性是,总结量的对数,然后采取总和的指数:
select
part_id,
sum(quantity) quantity
from (
select
part_id,
exp(sum(quantity_ln) over (partition by new_start order by r)) quantity
from (
select
r,
lvl,
part_id,
quantity_ln,
sum(new_start) over(order by r) new_start
from (
select
rownum r,
level lvl,
part_id,
ln(quantity) quantity_ln,
nvl(lag(connect_by_isleaf,1) over (order by rownum),0) new_start
from assembly
start with parent_part_id = 1
connect by parent_part_id = prior part_id
)
)
)
group by part_id
order by part_id
;
我很抱歉,但我不明白的问题*我怎么计算,以使顶层组件(部分1)需要各部分的总数是多少?*,并在相关说明,你如何得出预期的结果。 – 2011-01-24 20:16:00
@Rene - 第1部分是创建第一个平行结果的原始parent_part_id。如果我们看看这些结果,那么请注意,我们需要part_id 2中的2个,其中每个需要part_id 3中的10个 - 此分支对第3部分中的总数贡献20个,稍后以类似的方式需要10个第3部分,总共有30 – Randy 2011-01-24 20:24:13