Who does what in a database?
The DBA (Database Administrator) is the most powerful person. They are like the Building Manager. They decide who gets keys, they fix the plumbing (performance tuning), and they make sure the building doesn't collapse (backups).
The Application Programmer is the Architect/Builder. They design how the rooms look and build the doors (forms/interfaces). They write the SQL queries that the app uses, but they don't manage the hard drives.
The Naive User is the Tenant. They just walk in, sit on the sofa, and watch TV. They don't know (or care) how the building was built or how the plumbing works. They just click "Buy Now" and expect it to work.
Knowing roles helps in assigning permissions. You don't want a regular user deleting tables!
DBA: The Landlord (Has all keys). Programmer: The Builder (Makes doors). Naive User: The Tenant (Uses doors).
Role: The "Boss"