Question: Is Oracle Database in Cloud PaaS, IaaS, SaaS, or DBaaS?
Answer:

• If you install and manage Oracle database in cloud by yourself, then you are using it on IaaS.
• If you are just using it in cloud without installing or managing it, then it's PaaS.
• If you are configuring the database instance and have access to it through SQL*Net, then its DBaaS. 
• SaaS not really relevant when it comes to Oracle database in cloud as database mostly reside at the backend of applications whereas Saas is primarily all about applications.