SQL - Function to divide value among rows - sql

Question

I normally don't do database programming so Im rusty on how to do certain stuff. But I have an issue where I'm to take an item and if this item is in the same location but in different placements, divide the value of said item among the sum count between placements.
here is my table structure:
LOCATION PLACEMENT VALUE COUNT ITEM
25 12345 100 10 55555 <----
25 67890 100 20 55555 <----
25 11111 50 5 00000
25 22222 75 5 11111
In other words Item (55555) is in 2 placements and the value of this item is 100
The new value should be: PLACEMENT 12345 will be (10/30) *100 = 33.3 and PLACEMENT 67890 will be (20/30) * 100 = 66.7
Any idea how to do this in SQL or HQL?

Answer 1

create table new as
select item,count(distinct placement) as dist_placement,count(count)as count,sum(count) as s_count
from mytable
group by item,location;
hive> select * from new;
OK
00000 1 1 5
11111 1 1 5
55555 2 2 30
Create table final as
select b.location as location,b.placement as placement, CASE
WHEN a.count=2 and a.dist_placement=2 then cast(((b.count/a.s_count)*b.value) as double)
ELSE cast(b.value as double)
END , b.count as count, b.item as item
from new a
join mytable b
on a.item=b.item;
select * from final;
output
location placement value count item
25 12345 33.33333333333333 10 55555
25 67890 66.66666666666666 20 55555
25 11111 50.0 5 00000
25 22222 75.0 5 11111
if you give input with same placement and different item
LOCATION PLACEMENT VALUE COUNT ITEM
25 12345 100 10 55555 <----
25 12345 100 20 55555 <----
25 11111 50 5 00000
25 22222 75 5 11111
output will be
LOCATION PLACEMENT VALUE COUNT ITEM
25 12345 100.0 10 55555
25 12345 100.0 20 55555
25 11111 50.0 5 00000
25 22222 75.0 5 11111
May I right, let me know if you have other requirements.

Answer 2

There may be a more efficient way to do it, but in two steps you can add up the item_count and then create the new value by dividing it through.
create table new as select
item, sum(count) as item_count
from old
group by item, location, placement;
create table new2 as select
a.*,
b.item_count,
a.count/b.item_count as new_count
from old a
left join new b
on a.item=b.item;

Answer 3

Your sample table
SELECT * INTO #TEMP FROM
(
SELECT 25 LOCATION,12345 PLACEMENT,100 VALUE ,10 [COUNT], 55555 ITEM
UNION ALL
SELECT 25 , 67890 , 100 , 20,55555
UNION ALL
SELECT 25 , 11111 , 50 , 5,00000
UNION ALL
SELECT 25 , 22222 , 75 , 5, 11111
)TAB
Your result is below
SELECT *,
CAST(([COUNT]/CAST(SUM([COUNT]) OVER(PARTITION BY ITEM)AS NUMERIC(20,2)))*VALUE AS NUMERIC(20,1)) Result
FROM #TEMP