Unpivot on view nie działa w Oracle

Jak już powiedział Aleksej - nie będzie działać na serwerze Oracle w wersji <11g.

Oto stare i nieco „wstrętne” podejście...

select key, c1, c2, c3 from t order by key ;

KEY C1    C2    C3
--- ----- ----- -----
r1  v1    v2    v3
r2  v1    v2
r3  v1          v3
r4  v1
r5        v2    v3
r6        v2
r7              v3
r8

Możemy przekonwertować każdy wiersz wartości C1, C2 i C3 na trzy wiersze wartości w jednej kolumnie w następujący sposób.

break on key skip 1 duplicates
select key, 'C1' as source, c1 as val from t union all
select key, 'C2' as source, c2 as val from t union all
select key, 'C3' as source, c3 as val from t
order by key, source ;

KEY SOURCE VAL
--- ------ -----
r1  C1     v1
r1  C2     v2
r1  C3     v3
r2  C1     v1
r2  C2     v2
r2  C3
r3  C1     v1
r3  C2
r3  C3     v3
r4  C1     v1
r4  C2
r4  C3
r5  C1
r5  C2     v2
r5  C3     v3
r6  C1
r6  C2     v2
r6  C3
r7  C1
r7  C2
r7  C3     v3
r8  C1
r8  C2
r8  C3

Jeśli nie potrzebujemy wierszy z wartościami NULL z C1, C2 lub C3, możemy użyć klauzul WHERE, aby je odfiltrować.

select key, 'C1' as source, c1 as val from t where c1 is not null union all
select key, 'C2' as source, c2 as val from t where c2 is not null union all
select key, 'C3' as source, c3 as val from t where c3 is not null
order by key, source ;

KEY SOURCE VAL
--- ------ -----
r1  C1     v1
r1  C2     v2
r1  C3     v3
r2  C1     v1
r2  C2     v2
r3  C1     v1
r3  C3     v3
r4  C1     v1
r5  C2     v2
r5  C3     v3
r6  C2     v2
r7  C3     v3