Transposing and aggregating Oracle column data - sql

Question

I have the following data
Base End
RMSA Item 1
RMSA Item 2
RMSA Item 3
RMSB Item 1
RMSB Item 2
RMSC Item 4
I want to convert it to the following format
Key Products
RMSA;RMSB Item 1, Item 2
RMSA Item 3
RMSC Item 4
Basically, those with similar results should be grouped into 1 line. However, I can't seem to get it to work using listagg, etc since I'm grouping on two columns.
Is there any way to do this with a direct Oracle query?

Answer 1

You can use listagg() window analytic function twice as
with t1( Base, End ) as
(
select 'RMSA','Item 1' from dual union all
select 'RMSA','Item 2' from dual union all
select 'RMSA','Item 3' from dual union all
select 'RMSB','Item 1' from dual union all
select 'RMSB','Item 2' from dual union all
select 'RMSC','Item 4' from dual
),
t2 as
(
select
listagg(base,';') within group (order by end)
as key,
end
from t1
group by end
)
select key,
listagg(end,',') within group (order by end)
as Products
from t2
group by key
order by products;
Key Products
--------- --------------
RMSA;RMSB Item 1, Item 2
RMSA Item 3
RMSC Item 4
Demo

Answer 2

Below would be one way -
WITH base
AS (SELECT 'RMSA' AS base,
'Item 1' AS end1
FROM dual
UNION
SELECT 'RMSA' AS base,
'Item 2' AS end1
FROM dual
UNION
SELECT 'RMSA' AS base,
'Item 3' AS end1
FROM dual
UNION
SELECT 'RMSB' AS base,
'Item 1' AS end1
FROM dual
UNION
SELECT 'RMSB' AS base,
'Item 2' AS end1
FROM dual
UNION
SELECT 'RMSC' AS base,
'Item 4' AS end1
FROM dual),
t11
AS (SELECT t1.base base1,
t1.end1 AS end11,
t2.base base2,
t2.end1 AS end12
FROM base t1
inner join base t2
ON t1.end1 = t2.end1
WHERE t1.base > t2.base) SELECT
Concat(Concat(t11.base1, ';'), t11.base1),
Listagg(t11.end11, ',')
within GROUP (ORDER BY t11.end11)
FROM t11
GROUP BY Concat(Concat(t11.base1, ';'), t11.base1)
--above query will get you results where you have similar results
UNION
SELECT t1.base,
t1.end1
FROM base t1
left outer join t11
ON t1.base = t11.base1
AND t1.end1 = t11.end11
left outer join t11 t12
ON t1.base = t12.base2
AND t1.end1 = t12.end11
WHERE t11.base1 IS NULL
AND t12.base2 IS NULL;
Hope this helps