Oracle 11 R2 में common table expression
. के साथ यह संभव है :
परीक्षण डेटा:
-- 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);
चयन कथन:
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;
संपादित करें Ora11R2 से पहले, यह एक model clause
. के साथ काम कर सकता है :
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;
द्वितीय संपादित करें एक और संभावना यह होगी कि मात्रा के लघुगणक का योग किया जाए और फिर योग का घातांक लिया जाए:
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
;