Modeling your data

Data tables are hardly useful when they lie apart. In fact, by organizing them together in a database, we amplify their overall value as we unveil patterns and connections across data points. That is why data is typically stored in an ensemble of different tables connected with each other to virtually form a single body called a Data Model. When you work with multiple tables, it is beneficial to "visualize" what the underlying data model looks like: this gives you the ability to anticipate ways to leverage the data and interpret it correctly.

We shall bring the concept of a data model to life by going through a business example. Let's imagine that we own a small store selling musical instruments. Our business model is pretty simple: we order instruments from manufacturers and store them in a warehouse. Customers call at our shop and get the chance to try a few instruments before deciding whether to purchase or not. Our most loyal customers sign...