Seleccione una subconsulta que devuelva varias filas como cadena (una columna) en la tabla (Oracle SQL)

SQL Fiddle

Configuración del esquema Oracle 11g R2 :

CREATE TABLE Product ( Product_No, Column1, Column2 ) AS
SELECT 1, 'A', 10 FROM DUAL UNION ALL
SELECT 2, 'B', 11 FROM DUAL UNION ALL
SELECT 3, 'C', 12 FROM DUAL
/
CREATE TABLE Inventory ( Product_No, Inventory_No, ColumnA, ColumnB, ColumnC ) AS
SELECT 1, 1, 'ABC',  20,  30 FROM DUAL UNION ALL
SELECT 1, 2, 'DDD',  30,  50 FROM DUAL UNION ALL
SELECT 2, 1, 'EFG',  60,  70 FROM DUAL UNION ALL
SELECT 2, 2, 'CDE',  99, 100 FROM DUAL UNION ALL
SELECT 3, 3, 'EFF', 120,  30 FROM DUAL
/

Consulta 1 :

SELECT p.*, i.ColumnX
FROM   Product p
       LEFT OUTER JOIN
       ( SELECT Product_no,
                LISTAGG(
                  ColumnA || '-' || ColumnB || '-' || ColumnC,
                  ','
                ) WITHIN GROUP ( ORDER BY Inventory_no )
                AS ColumnX
         FROM   Inventory
         GROUP BY Product_No
       ) i
       ON ( p.product_no = i.product_no )

Resultados :

| PRODUCT_NO | COLUMN1 | COLUMN2 |              COLUMNX |
|------------|---------|---------|----------------------|
|          1 |       A |      10 |  ABC-20-30,DDD-30-50 |
|          2 |       B |      11 | EFG-60-70,CDE-99-100 |
|          3 |       C |      12 |           EFF-120-30 |