@akhyyl - welcome to Bubble. What you’re exploring are the basic concepts of a relational database. More specifically, a relational database allows you to create associations by linking together data points.
For example, with your app, you already have three of the primary data types you need (User, UserComment and Review). Bubble does some heavy lifting for you by saving the database fields of when something was created, last modified and who created it. (For example, when a user creates a review, you automatically know which user created it, because Bubble saves that for you).
However, Bubble doesn’t know the secondary relationships. That’s where your programming comes in - you’re creating the relationships between data types. For example, on a “UserComment”, you would create a new “Field” which has the data type of “Review”. Then, when the “UserComment” is created, you also reference the parent “Review” (Conversely, you can create a field called “Associated_Comments” on the data type “Review”, which is a list of all of the “UserComments”
I recommend checking out my LearnTo lesson on “How to build a grocery list app”. It’ll give you a good understanding of how to get the basics of a database set up.
Dan (creator of LearnTo - 15+ hours of Bubble tutorials and live coaching)