Oracle SQL Select Query Getting Max Row As a Fraction of a Rollup Total - oracle

Question

hoping I might be able to get some advise regarding Oracle SQL…
I have a table roughly as follows (there are more columns, but not necessary for this example)…
LOCATION USER VALUE
1 1 10
1 2 20
1 3 30
2 4 10
2 5 10
2 6 20
1 60
2 40
100
I’ve used rollup to get subtotals.
What I need to do is get the max(value) row for each location and express the max(value) as a percentage or fraction of the subtotal for each location
ie:
LOCATION USER FRAC
1 3 0.5
2 6 0.5
I could probably solve this using my limited knowledge of select queries, but am guessing there must be a fairly quick and slick method..
Thanks in advance :)

Answer 1

Solution using analytic functions
(Please note the WITH MY_TABLE AS serving only as dummy datasource)
WITH MY_TABLE AS
( SELECT 1 AS LOC_ID,1 AS USER_ID, 10 AS VAL FROM DUAL
UNION
SELECT 1,2,20 FROM DUAL
UNION
SELECT 1,3,30 FROM DUAL
UNION
SELECT 2,4,10 FROM DUAL
UNION
SELECT 2,5,10 FROM DUAL
UNION
SELECT 2,6,20 FROM DUAL
)
SELECT LOC_ID,
USER_ID,
RATIO_IN_LOC
FROM
(SELECT LOC_ID,
USER_ID,
RATIO_IN_LOC,
RANK() OVER (PARTITION BY LOC_ID ORDER BY RATIO_IN_LOC DESC) AS ORDER_IN_LOC
FROM
(SELECT LOC_ID,
USER_ID,
VAL,
VAL/SUM(VAL) OVER (PARTITION BY LOC_ID) AS RATIO_IN_LOC
FROM MY_TABLE
)
)
WHERE ORDER_IN_LOC = 1
ORDER BY LOC_ID,
USER_ID;
Result
LOC_ID USER_ID RATIO_IN_LOC
1 3 0,5
2 6 0,5

Answer 2

with inputs ( location, person, value ) as (
select 1, 1, 10 from dual union all
select 1, 2, 20 from dual union all
select 1, 3, 30 from dual union all
select 2, 4, 10 from dual union all
select 2, 5, 10 from dual union all
select 2, 6, 20 from dual
),
prep ( location, person, value, m_value, total ) as (
select location, person, value,
max(value) over (partition by location),
sum(value) over (partition by location)
from inputs
)
select location, person, round(value/total, 2) as frac
from prep
where value = m_value;
Notes: Your table exists already? Then skip everything from "inputs" to the comma; your query should begin with with prep (...) as ( ...
I changed user to person since user is a keyword in Oracle, you shouldn't use it for table or column names (actually you can't unless you use double quotes, which is a very poor practice).
The query will output two or three or more rows per location if there are ties at the top. Presumably this is what you desire.
Output:
LOCATION PERSON FRAC
---------- ---------- ----------
1 3 .5
2 6 .5