Hvordan kontrollerer du for matchende værdi i tredje kolonne baseret på forskellige kombinationer af to andre kolonner?

Du kan group by building, location for rækkerne where object in ('WALL', 'WINDOW') :

select building, location, 'FLAG' action
from tablename
where object in ('WALL', 'WINDOW')
group by building, location
having count(distinct object) < 2

Betingelsen count(distinct object) < 2 i having klausul returnerer en kombination af building, location hvor 'WALL' og 'WINDOW' eksisterer ikke begge dele.
Se demoen .
Resultater:

| building | location | action |
| -------- | -------- | ------ |
| A        | FLOOR2   | FLAG   |
| B        | FLOOR1   | FLAG   |

Eller med IKKE FINDER:

select t.building, t.location, 'FLAG' action
from tablename t
where object in ('WALL', 'WINDOW')
and not exists (
  select 1 from tablename
  where building = t.building and location = t.location and object <> t.object
)

Se demoen .