I understand that a component is an Aggregate if it is "a part of" another component, which leads me to believe that a "Loan" is "Part Of" the Loan Database. However, the loan database cannot exist without the loan - which leads me to believe it may just be an association.
Any help is appreciated and I already reviewed these:
uml-association-vs-composition-and-detail-level
What is the difference between association, aggregation and composition?
I don't know what you think a loan database should be. But any database can exist even if it has no content at all. Go and create an arbitrary database. You can do that. It has no data - and no structure. The first you do is to create the structure then (e.g. a loan structure). Only then you add single elements (rows or loan entries) to your database.
Generally you should not care too much about composition at all. It really does not add much semantics to your model. A composite aggregation makes sense in cases where you have security issues (you must get rid of related data) or where memory management is important. Shared aggregation is even evil I'd say since it has no fixed defined semantics. The UML specs explicitly states that you need to define the semantics in your domain before using it.
tl;dr; Don't use composition and focus on the correct associations preferably with the right multiplicity and if possible good role names.
