Ниже будет один путь -
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;
Надеюсь, это поможет