There is a composition between these: Host-> Database(oracle) Doesn't work the other way around. I suppose you could create an enrichment that adds an opposite direction 'dependency' between them, and also some link between environment and database (like membership maybe?).
It would be easier to advise if you could present some screenshot.
But as i am novice to ucmdb so don't much about it . As i have searched about the Enrichment rule new question arises whether it is temporary or permanent whether it will affect the existing query through which we can see the oracle devices as already in the system or it will provide the result that i want and what it impact over the existing environment?